'annihilation' originates from Latin, specifically the verb 'annihilare' (and the noun 'annihilatio'), where the element 'ad-' (assimilated to 'an-') meant 'to/toward' and 'nihil' meant 'nothing'.

'annihilare' passed into Late Latin as 'annihilatio' and then into Medieval and Middle English (e.g. Middle English 'annihilacioun'), eventually becoming the modern English word 'annihilation'.

Initially it meant 'the action of reducing to nothing' or 'making nothing', and over time it kept that core sense while also gaining specialized physical usage (matter–antimatter annihilation) and figurative senses like 'complete defeat'.