'irritate' originates from Latin, specifically the word 'irritare', where the root meant 'to provoke, excite'.

'irritate' passed into English from Late Latin 'irritare' (and Old French 'irriter'), eventually becoming the modern English 'irritate'.

Initially it meant 'to provoke or stimulate (emotion or action)'; over time this shifted toward the common senses 'to annoy' and 'to cause inflammation or soreness'.