'annihilator' originates from Latin, specifically the word 'annihilare', where the elements 'ad-' (or assimilated form 'an-') meant 'to' or 'toward' and 'nihil' meant 'nothing'.

'annihilator' developed from the Latin verb 'annihilare' (to reduce to nothing), which passed into English as the verb 'annihilate' and later formed the agent noun 'annihilator' by adding the suffix '-or'.

Initially, the Latin root meant 'to reduce to nothing'; over time this evolved into the English sense of 'one that destroys completely' and specialized technical senses (e.g., algebraic annihilator, annihilation operator).