From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Fundamentalism

Fundamentalism usually has a religious connotation that indicates unwavering attachment to a set of irreducible beliefs. However, fundamentalism has come to be applied to a tendency among certain groups – mainly, although not exclusively, in religion – that is characterized by a markedly strict literalism as it is applied to certain specific scriptures, dogmas, or ideologies, and a strong sense of the importance of maintaining ingroup and outgroup distinctions, leading to an emphasis on purity and the desire to return to a previous ideal from which advocates believe members have strayed. Rejection of diversity of opinion as applied to these established "fundamentals" and their accepted interpretation within the group often results from this tendency.

Depending upon the context, the label "fundamentalism" can be a pejorative rather than a neutral characterization, similar to the ways that calling political perspectives "right-wing" or "left-wing" can have negative connotations.

Buddhism