'anti-fascist' is formed from the prefix 'anti-' (from Greek 'anti-' meaning 'against') combined with 'fascist' (from Italian 'fascista', relating to 'fascismo').

'fascist' comes from Italian 'fascista' and 'fascismo' (from 'fascio' meaning 'bundle' or 'group'); the compound 'anti-fascist' arose in English in the early 20th century (notably the 1920s–1930s) to describe those opposed to fascist movements.

Initially it specifically described opposition to interwar and WWII-era fascist movements; over time it has retained that meaning and is also used more broadly for opposition to contemporary authoritarian or ultra-nationalist movements.