'antproof' originates from Modern English, specifically formed as a compound of the Old English-derived word 'ant' (from Old English 'ǣmete', meaning 'ant') and the word 'proof' (from Old English/Middle English 'prōf'/'prove', ultimately from Latin 'probare', meaning 'to test' or 'to make resistant').

'ant' developed from Old English 'ǣmete' into Middle and then Modern English 'ant'; 'proof' came into English via Old French and Middle English (forms like 'proef'/'prove') and was used as a combining element in compounds (e.g. 'waterproof'). The compound began appearing in patterns like 'ant-proof' in recent centuries and is now written as 'antproof' or 'ant-proof' in modern use.

Initially the parts referred separately to the insect ('ant') and the idea of being 'proof' or resistant; combined as 'antproof' the meaning became the straightforward compound sense 'resistant to ants', which has remained stable.