peen, n. & v.
--n. the wedge-shaped or thin or curved end of a hammer-head (opp. FACE n. 5a).
--v.tr.
1 hammer with a peen.
2 treat (sheet metal) with a stream of metal shot in order to shape it.
17th c.: also pane, app. f. F panne f. Du. pen f. L pinna point