'nonirritant' originates from the prefix 'non-' (from Latin 'non') and the adjective 'irritant' (from Latin 'irritare'), where 'non-' meant 'not' and 'irritare' meant 'to provoke or excite'.

'irritant' came into English via Latin 'irritare' and Old French forms meaning 'to provoke', becoming Middle English forms and modern English 'irritant'; 'nonirritant' is a Modern English formation created by adding the prefix 'non-' to 'irritant'.

Initially, 'irritare' meant 'to provoke or excite'; over time 'irritant' came to mean 'something that causes irritation', and 'nonirritant' developed as the negated form meaning 'not causing irritation'.