wen 1 |wen|nouna boil or other swelling or growth on the skin, esp. a sebaceous cyst.• archaic an outstandingly large or overcrowded city the great wen of London.ORIGIN Old English wen(n), of unknown origin; compare with Low German wehne ‘tumor, wart.’wen 2 (also wyn |win|)nounrunic letter, used in Old and Middle English, later replaced by w.ORIGIN Old English , literally [joy] ; so named because it is the first letter of this word. Compare with sense 3 of thorn and sense 2 of ash .