subs. phr. (colloquial).1. A man, woman, or thing of decided and undoubted merit. Cf., GOOD-GIRL.
1836. HOOD, Miss Kilmansegg and Her Precious Leg [Works (1846), vi. 254]. A GOOD UN to look at but bad to go.
1854. MARTIN and AYTOUN, Bon Gaultier Ballads. The Dirge of a Drinker. Like a GOOD UN as he is.
1891. N. GOULD, The Double Event, p. 160. Hes a real GOOD UN, and when his party plank the stuff down its generally a moral.
2. (colloquial).An expression of derisive unbelief: e.g., a lie. See WHOPPER.