'unpicked' originates from Old English prefix 'un-' and Middle English (from Middle Dutch/Low German) 'piken'/'pikken', where 'un-' meant 'not' and 'piken'/'pikken' meant 'to pick, peck'.

'unpicked' changed from Middle English formation 'unpiken' (from 'un-' + 'piken') and later became Modern English 'unpick' with past/past-participle 'unpicked'.

Initially, it meant 'to reverse or undo picking (to pick apart or undo stitches)', and over time it has come to be used both as the past/past-participle of 'unpick' and as an adjective meaning 'not picked' or 'left unpicked'.