'idolator' originates from Late Latin, specifically the word 'idololatra', where 'idol(o)-' (from Greek 'eidōlon') meant 'image' and '-latra' (from Greek 'latreia') meant 'worship'.

'idolator' changed from Greek 'eidōlolatrēs' to Late Latin 'idololatra', then via Middle English 'idolater' to the modern English form 'idolator'.

Initially, it meant 'one who worships images (idols)'; over time the sense has remained but also broadened figuratively to mean 'one who shows excessive admiration for a person or thing'.