\Peen\, n. [Cf. G. pinne pane of a hammer.]
(a) A round-edged, or hemispherical, end to the head of a
    hammer or sledge, used to stretch or bend metal by
    indentation.
(b) The sharp-edged end of the head of a mason's hammer.
    [Spelt also {pane}, {pein}, and {piend}.]

\Peen\, v. t.
To draw, bend, or straighten, as metal, by blows with the
peen of a hammer or sledge.