'anticapitalist' is formed in modern English from the prefix 'anti-' (from Greek 'anti-' meaning 'against') + 'capitalist' (one who supports or owns capital).

'capitalist' derives from French/Medieval Latin 'capitalis' (from Latin 'caput' meaning 'head'); 'capital' came to mean wealth or assets, and 'capitalist' developed in the 19th century to mean someone owning or investing capital. 'anti-' (Greek) was attached in English to create 'anticapitalist' by the late 19th / early 20th century.

Initially formed simply as 'anti-' + 'capitalist' to denote opposition to capitalism; the modern sense remains opposition to capitalist economic systems or principles.