'anti-fundamentalism' originates from combining the prefix 'anti-' (from Greek anti- meaning 'against') with 'fundamentalism' (the noun formed from 'fundamental' + suffix '-ism'), where 'fundamental' derives from Latin 'fundamentum' meaning 'foundation'.

'Fundamentalism' arose in early 20th-century English to describe a movement defending certain religious 'fundamentals'; 'anti-' was prefixed to form 'anti-fundamentalism' when describing opposition to that movement and, later, to similar strict doctrines in other fields.

Initially it referred specifically to opposition to the early 20th-century religious movement called 'Fundamentalism'; over time it broadened to mean opposition to strict, literal, or uncompromising adherence to foundational principles in religion, politics, and culture.