'anti-realism' is formed from the prefix 'anti-' (from Greek 'anti' meaning 'against') combined with 'realism' (from French 'réalisme' and Latin roots related to 'res', 'thing').

The element 'realism' entered English from French 'réalisme' (ultimately from Latin 'realis' related to 'res' meaning 'thing'), and the compound 'anti-realism' arose in modern philosophical usage (20th century) to denote positions opposing various forms of realism; the term was popularized in debates in analytic philosophy in the mid- to late-20th century.

Originally a literal compound meaning 'against realism', it developed into a technical label for a range of philosophical doctrines that deny mind-independent existence or objectivity in specific domains (e.g., mathematics, ethics, science).