'anti-animalist' originates from the Greek-derived prefix 'anti-' (from Greek 'antí') meaning 'against' combined with the Latin root 'animal' (from Latin 'animalis'), plus the English agentive suffix '-ist' forming 'one who holds a position'.

'animal' entered English from Latin 'animalis' (via Old French/Medieval Latin) and became Middle/Modern English 'animal'; the modern compound 'anti-animalist' is formed in English by combining the prefix 'anti-' with 'animal' and the suffix '-ist'.

Initially, the components meant 'against' + 'living creature' + 'person who holds a view'; over time the compound has come to mean specifically 'someone opposed to granting moral or legal consideration to animals (or to animal-rights positions)'.