'downy' originates from English, formed from 'down' + suffix '-y'. 'down' ultimately comes from Old English 'dūn', meaning 'down (soft feathers)'.

'downy' developed in Middle English from forms such as 'douny' or 'downy' (derived from 'down') and eventually became the modern English adjective 'downy'.

Initially associated specifically with the fine feathers called 'down'; over time it came to mean more generally 'covered with or resembling soft fine fluff' or 'having a soft, velvety surface'.