'antilog' originates from Modern English as a shortening of 'antilogarithm', ultimately built from Greek elements: prefix 'anti-' meant 'against' or 'opposite', and 'logarithm' comes from Greek 'logarithmos' (from 'logos' meaning 'ratio' or 'reason').

'antilog' developed as a clipped form of 'antilogarithm' (coined in the early 19th century from 'anti-' + 'logarithm'); the longer form 'antilogarithm' itself derives from New Latin/Greek formation of 'logarithm' + the prefix 'anti-'.

Initially it meant 'the inverse of a logarithm' (i.e., the number whose logarithm is the given value); this technical meaning has remained stable in mathematical usage.