'antiegoistical' originates from Modern English, specifically formed from the prefix 'anti-' (from Greek 'anti' via Latin/Old French usage) and the adjective 'egoistical' (from Latin 'ego' meaning 'I'), where 'anti-' meant 'against' and 'ego' meant 'I'.

'antiegoistical' developed as a compound of 'anti-' + 'egoistical'. 'Ego' comes from Latin 'ego'; French formed words such as 'égoïste' which influenced English 'egoist'/'egoistic' and then 'egoistical'; 'anti-' was attached (often first hyphenated as 'anti-egoistical') and later became a single-word form 'antiegoistical' in modern English.

Initially it literally meant 'against egoism' (i.e., opposed to self-centeredness or the doctrine of egoism), and over time the term has been used both to describe ideological opposition to egoism and more generally to describe persons or attitudes that are 'not egoistical' (unselfish).