https://en.wikipedia.org/wiki/Semantics
  
In International scientific vocabulary semantics is also called semasiology. The word semantics was first used by Michel Bréal, a French philologist. It denotes a range of ideas—from the popular to the highly technical. It is often used in ordinary language for denoting a problem of understanding that comes down to word selection or connotation. This problem of understanding has been the subject of many formal enquiries, over a long period of time, especially in the field of formal semantics. In linguistics, it is the study of the interpretation of signs or symbols used in agents or communities within particular circumstances and contexts. Within this view, sounds, facial expressions, body language, and proxemics have semantic (meaningful) content, and each comprises several branches of study. In written language, things like paragraph structure and punctuation bear semantic content; other forms of language bear other semantic content.
The formal study of semantics intersects with many other fields of inquiry, including lexicology, syntax, pragmatics, etymology and others. Independently, semantics is also a well-defined field in its own right, often with synthetic properties. In the philosophy of language, semantics and reference are closely connected. Further related fields include philology, communication, and semiotics. The formal study of semantics can therefore be manifold and complex.
Semantics contrasts with syntax, the study of the combinatorics of units of a language (without reference to their meaning), and pragmatics, the study of the relationships between the symbols of a language, their meaning, and the users of the language. Semantics as a field of study also has significant ties to various representational theories of meaning including truth theories of meaning, coherence theories of meaning, and correspondence theories of meaning. Each of these is related to the general philosophical study of reality and the representation of meaning. In 1960s psychosemantic studies became popular after Osgood's massive cross-cultural studies using his semantic differential (SD) method that used thousands of nouns and adjective bipolar scales. A specific form of the SD, Projective Semantics method uses only most common and neutral nouns that correspond to the 7 groups (factors) of adjective-scales most consistently found in cross-cultural studies (Evaluation, Potency, Activity as found by Osgood, and Reality, Organization, Complexity, Limitation as found in other studies). In this method, seven groups of bipolar adjective scales corresponded to seven types of nouns so the method was thought to have the object-scale symmetry (OSS) between the scales and nouns for evaluation using these scales. For example, the nouns corresponding to the listed 7 factors would be: Beauty, Power, Motion, Life, Work, Chaos, Law. Beauty was expected to be assessed unequivocally as “very good” on adjectives of Evaluation-related scales, Life as “very real” on Reality-related scales, etc. However, deviations in this symmetric and very basic matrix might show underlying biases of two types: scales-related bias and objects-related bias. This OSS design meant to increase the sensitivity of the SD method to any semantic biases in responses of people within the same culture and educational background.
Semantics (from Ancient Greek: σημαντικός sēmantikós, "significant") is the linguistic and philosophical study of meaning in language, programming languages, formal logics, and semiotics. It is concerned with the relationship between signifiers—like words, phrases, signs, and symbols—and what they stand for in reality, their denotation. 
In International scientific vocabulary semantics is also called semasiology. The word semantics was first used by Michel Bréal, a French philologist. It denotes a range of ideas—from the popular to the highly technical. It is often used in ordinary language for denoting a problem of understanding that comes down to word selection or connotation. This problem of understanding has been the subject of many formal enquiries, over a long period of time, especially in the field of formal semantics. In linguistics, it is the study of the interpretation of signs or symbols used in agents or communities within particular circumstances and contexts. Within this view, sounds, facial expressions, body language, and proxemics have semantic (meaningful) content, and each comprises several branches of study. In written language, things like paragraph structure and punctuation bear semantic content; other forms of language bear other semantic content.
The formal study of semantics intersects with many other fields of inquiry, including lexicology, syntax, pragmatics, etymology and others. Independently, semantics is also a well-defined field in its own right, often with synthetic properties. In the philosophy of language, semantics and reference are closely connected. Further related fields include philology, communication, and semiotics. The formal study of semantics can therefore be manifold and complex.
Semantics contrasts with syntax, the study of the combinatorics of units of a language (without reference to their meaning), and pragmatics, the study of the relationships between the symbols of a language, their meaning, and the users of the language. Semantics as a field of study also has significant ties to various representational theories of meaning including truth theories of meaning, coherence theories of meaning, and correspondence theories of meaning. Each of these is related to the general philosophical study of reality and the representation of meaning. In 1960s psychosemantic studies became popular after Osgood's massive cross-cultural studies using his semantic differential (SD) method that used thousands of nouns and adjective bipolar scales. A specific form of the SD, Projective Semantics method uses only most common and neutral nouns that correspond to the 7 groups (factors) of adjective-scales most consistently found in cross-cultural studies (Evaluation, Potency, Activity as found by Osgood, and Reality, Organization, Complexity, Limitation as found in other studies). In this method, seven groups of bipolar adjective scales corresponded to seven types of nouns so the method was thought to have the object-scale symmetry (OSS) between the scales and nouns for evaluation using these scales. For example, the nouns corresponding to the listed 7 factors would be: Beauty, Power, Motion, Life, Work, Chaos, Law. Beauty was expected to be assessed unequivocally as “very good” on adjectives of Evaluation-related scales, Life as “very real” on Reality-related scales, etc. However, deviations in this symmetric and very basic matrix might show underlying biases of two types: scales-related bias and objects-related bias. This OSS design meant to increase the sensitivity of the SD method to any semantic biases in responses of people within the same culture and educational background.
Linguistics
In linguistics, semantics
 is the subfield that is devoted to the study of meaning, as inherent at
 the levels of words, phrases, sentences, and larger units of discourse (termed texts, or narratives).
 The study of semantics is also closely linked to the subjects of 
representation, reference and denotation. The basic study of semantics 
is oriented to the examination of the meaning of signs, and the study of relations between different linguistic units and compounds: homonymy, synonymy, antonymy, hypernymy, hyponymy, meronymy, metonymy, holonymy,
 paronyms. A key concern is how meaning attaches to larger chunks of 
text, possibly as a result of the composition from smaller units of 
meaning. Traditionally, semantics has included the study of sense and denotative reference, truth conditions, argument structure, thematic roles, discourse analysis, and the linkage of all of these to syntax. 
Montague grammar
In the late 1960s, Richard Montague proposed a system for defining semantic entries in the lexicon in terms of the lambda calculus. In these terms, the syntactic parse of the sentence John ate every bagel would consist of a subject (John) and a predicate (ate every bagel);
 Montague demonstrated that the meaning of the sentence altogether could
 be decomposed into the meanings of its parts and in relatively few 
rules of combination. The logical predicate thus obtained would be 
elaborated further, e.g. using truth theory models, which ultimately 
relate meanings to a set of Tarskian universals, which may lie outside the logic. The notion of such meaning atoms or primitives is basic to the language of thought hypothesis from the 1970s.
Despite its elegance, Montague grammar was limited by the context-dependent variability in word sense, and led to several attempts at incorporating context, such as:
- Situation semantics (1980s): truth-values are incomplete, they get assigned based on context
 - Generative lexicon (1990s): categories (types) are incomplete, and get assigned based on context
 
Prototype theory
Another set of concepts related to fuzziness in semantics is based on prototypes. The work of Eleanor Rosch
 in the 1970s led to a view that natural categories are not 
characterizable in terms of necessary and sufficient conditions, but are
 graded (fuzzy at their boundaries) and inconsistent as to the status of
 their constituent members. One may compare it with Jung's archetype, though the concept of archetype sticks to static concept. Some post-structuralists are against the fixed or static meaning of the words. Derrida, following Nietzsche, talked about slippages in fixed meanings. 
Systems of categories are not objectively out there in the world but are rooted in people's experience. These categories evolve as learned
 concepts of the world – meaning is not an objective truth, but a 
subjective construct, learned from experience, and language arises out 
of the "grounding of our conceptual systems in shared embodiment and bodily experience".
A corollary of this is that the conceptual categories (i.e. the lexicon)
 will not be identical for different cultures, or indeed, for every 
individual in the same culture. This leads to another debate.
Theories in semantics
Formal semantics
Originates from Montague's work (see above). A highly formalized 
theory of natural language semantics in which expressions are assigned 
denotations (meanings) such as individuals, truth values, or functions 
from one of these to another. The truth of a sentence, and its logical 
relation to other sentences, is then evaluated relative to a model. 
Truth-conditional semantics
Pioneered by the philosopher Donald Davidson,
 another formalized theory, which aims to associate each natural 
language sentence with a meta-language description of the conditions 
under which it is true, for example: 'Snow is white' is true if and only
 if snow is white. The challenge is to arrive at the truth conditions 
for any sentences from fixed meanings assigned to the individual words 
and fixed rules for how to combine them. In practice, truth-conditional 
semantics is similar to model-theoretic semantics; conceptually, 
however, they differ in that truth-conditional semantics seeks to 
connect language with statements about the real world (in the form of 
meta-language statements), rather than with abstract models.
Conceptual semantics
This theory is an effort to explain properties of argument structure.
 The assumption behind this theory is that syntactic properties of 
phrases reflect the meanings of the words that head them.
 With this theory, linguists can better deal with the fact that subtle 
differences in word meaning correlate with other differences in the 
syntactic structure that the word appears in. The way this is gone about is by looking at the internal structure of words. These small parts that make up the internal structure of words are termed semantic primitives.
Cognitive semantics
Cognitive semantics approaches meaning from the perspective of cognitive linguistics. In this framework, language is explained via general human cognitive abilities rather than a domain-specific language module. The techniques native to cognitive semantics are typically used in lexical studies such as those put forth by Leonard Talmy, George Lakoff, Dirk Geeraerts, and Bruce Wayne Hawkins.
 Some cognitive semantic frameworks, such as that developed by Talmy, 
take into account syntactic structures as well. Semantics, through 
modern researchers can be linked to the Wernicke's area of the brain and
 can be measured using the event-related potential (ERP). ERP is the 
rapid electrical response recorded with small disc electrodes which are 
placed on a persons scalp. 
Lexical semantics
A linguistic theory that investigates word meaning. This theory 
understands that the meaning of a word is fully reflected by its 
context. Here, the meaning of a word is constituted by its contextual 
relations. Therefore, a distinction between degrees of participation as well as modes of participation are made.
 In order to accomplish this distinction any part of a sentence that 
bears a meaning and combines with the meanings of other constituents is 
labeled as a semantic constituent. Semantic constituents that cannot be 
broken down into more elementary constituents are labeled minimal 
semantic constituents.
Cross-cultural semantics
Various fields or disciplines have long been contributing to cross-cultural semantics. Are words like love, truth, and hate universals? Is even the word sense – so central to semantics – a universal, or a concept entrenched in a long-standing but culture-specific tradition?
 These are the kind of crucial questions that are discussed in 
cross-cultural semantics. Translation theory, ethnolinguistics, 
linguistic anthropology and cultural linguistics specialize in the field
 of comparing, contrasting, and translating words, terms and meanings 
from one language to another (see Herder, W. von Humboldt, Boas, Sapir, 
and Whorf). But philosophy, sociology, and anthropology have long 
established traditions in contrasting the different nuances of the terms
 and concepts we use. And online encyclopaedias such as the Stanford 
encyclopedia of philosophy, https://plato.stanford.edu,
 and more and more Wikipedia itself have greatly facilitated the 
possibilities of comparing the background and usages of key cultural 
terms. In recent years the question of whether key terms are 
translatable or untranslatable has increasingly come to the fore of 
global discussions, especially since the publication of Barbara Cassin’s
 Dictionary of Untranslatables: A Philosophical Lexicon, in 2014.
Computational semantics
Computational semantics is focused on the processing of linguistic 
meaning. In order to do this concrete algorithms and architectures are 
described. Within this framework the algorithms and architectures are 
also analyzed in terms of decidability, time/space complexity, data 
structures that they require and communication protocols.
Computer science
In computer science, the term semantics refers to the meaning of language constructs, as opposed to their form (syntax).
 According to Euzenat, semantics "provides the rules for interpreting 
the syntax which do not provide the meaning directly but constrains the 
possible interpretations of what is declared."
Programming languages
The semantics of programming languages and other languages is an important issue and area of study in computer science. Like the syntax of a language, its semantics can be defined exactly. 
For instance, the following statements use different syntaxes, 
but cause the same instructions to be executed, namely, perform an 
arithmetical addition of 'y' to 'x' and store the result in a variable 
called 'x':
| Statement | Programming languages | 
|---|---|
x += y
 | 
C, C++, C#, Java, JavaScript, Python, Ruby, etc. | 
$x += $y
 | 
Perl, PHP | 
x := x + y
 | 
Ada, ALGOL, ALGOL 68, BCPL, Dylan, Eiffel, Modula-2, Oberon, OCaml, Object Pascal (Delphi), Pascal, SETL, Simula, Smalltalk, Standard ML, VHDL, etc. | 
MOV EAX,[y] ADD [x],EAX
 | 
Assembly languages: Intel 8086 | 
ldr     r2, [y]ldr     r3, [x]add     r3, r3, r2str     r3, [x]
 | 
Assembly languages: ARM | 
LET X = X + Y
 | 
BASIC: early | 
x = x + y
 | 
BASIC: most dialects; Fortran, MATLAB, Lua | 
Set x = x + y
 | 
Caché ObjectScript | 
ADD Y TO X.
 | 
ABAP | 
ADD Y TO X GIVING X
 | 
COBOL | 
set /a x=%x%+%y%
 | 
Batch | 
(incf x y)
 | 
Common Lisp | 
/x y x add def
 | 
PostScript | 
y @ x +! 
 | 
Forth | 
x =: x + y 
 | 
J | 
Various ways have been developed to describe the semantics of programming languages formally, building on mathematical logic:
- Operational semantics: The meaning of a construct is specified by the computation it induces when it is executed on a machine. In particular, it is of interest how the effect of a computation is produced.
 - Denotational semantics: Meanings are modelled by mathematical objects that represent the effect of executing the constructs. Thus only the effect is of interest, not how it is obtained.
 - Axiomatic semantics: Specific properties of the effect of executing the constructs are expressed as assertions. Thus there may be aspects of the executions that are ignored.
 
Semantic models
The Semantic Web refers to the extension of the World Wide Web via embedding added semantic metadata, using semantic data modeling techniques such as Resource Description Framework (RDF) and Web Ontology Language (OWL).
On the Semantic Web, terms such as semantic network and semantic data model are used to describe particular types of data model characterized by the use of directed graphs
 in which the vertices denote concepts or entities in the world and 
their properties, and the arcs denote relationships between them. These 
can formally be described as description logic concepts and roles, which correspond to OWL classes and properties.
Psychology
In psychology, semantic memory is memory for meaning – in other words, the aspect of memory that preserves only the gist, the general significance, of remembered experience – while episodic memory
 is memory for the ephemeral details – the individual features, or the 
unique particulars of experience. The term 'episodic memory' was 
introduced by Tulving and Schacter in the context of 'declarative 
memory' which involved simple association of factual or objective 
information concerning its object. Word meaning is measured by the 
company they keep, i.e. the relationships among words themselves in a semantic network.
 The memories may be transferred intergenerationally or isolated in one 
generation due to a cultural disruption. Different generations may have 
different experiences at similar points in their own time-lines. This 
may then create a vertically heterogeneous semantic net for certain 
words in an otherwise homogeneous culture. In a network created by people analyzing their understanding of the word (such as Wordnet) the links and decomposition structures of the network are few in number and kind, and include part of, kind of, and similar links. In automated ontologies
 the links are computed vectors without explicit meaning. Various 
automated technologies are being developed to compute the meaning of 
words: latent semantic indexing and support vector machines as well as natural language processing, artificial neural networks and predicate calculus techniques.
Ideasthesia
 is a psychological phenomenon in which activation of concepts evokes 
sensory experiences. For example, in synesthesia, activation of a 
concept of a letter (e.g., that of the letter A) evokes sensory-like experiences (e.g., of red color).