'antiworld' originates from Greek and Old English, specifically the prefix 'anti-' from Greek 'anti' meaning 'against' or 'opposite', and the word 'world' from Old English 'weoruld' meaning 'age' or 'human existence'.

'anti-' entered English as a combining form from Greek via Latin and later usage in Medieval and Early Modern English; 'world' evolved from Old English 'weoruld' through Middle English 'world'. The compound 'antiworld' is a modern coinage formed by combining these elements.

Initially the components separately meant 'against' (anti-) and 'age/human existence' (world); together in modern usage they evolved into the composite sense 'a world that opposes or mirrors our world', used mainly in fiction and speculative contexts.