peen noun. 
[pi:n] Also 
pein. 
L17.[Origin uncertain: cf. PEEN verb, PANE noun2.]The end of a hammer head opposite to the face, esp. when sharp. 
 [TahlilGaran] English Dictionary ▲
 peen verb trans. [pi:n] E16.[App. of Norse origin: cf. Swedish dial. pena, päne, Danish dial. pene, paene, Norwegian dial penna, paenna.]Beat thin with a hammer, hammer 
out; strike with the peen of a hammer. 
 [TahlilGaran] English Dictionary ▲