'anisocoria' originates from Greek via New Latin, specifically from the Greek elements 'anisos' meaning 'unequal' (from 'a-' not + 'isos' equal) and 'korē' meaning 'pupil'.

'anisocoria' was formed as a medical/neologistic term in New Latin (and Modern medical usage) from Greek roots 'anisos' + 'korē' and was adopted into English medical vocabulary in the 19th century.

Initially it referred specifically to the state of 'unequal pupils' (from the Greek root meaning 'unequal pupil'), and that core meaning has been retained in modern medical usage.