from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The end of a hammerhead opposite the flat striking surface, often wedge-shaped or ball-shaped and used for chipping, indenting, and metalworking.
  • transitive v. To hammer, bend, or shape with a peen.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The (often spherical) end of the head of a hammer opposite the main hammering end.
  • v. To shape metal by striking it, especially with a peen.
  • n. Penis.

from the GNU version of the Collaborative International Dictionary of English

  • n. A round-edged, or hemispherical, end to the head of a hammer or sledge, used to stretch or bend metal by indentation.
  • n. The sharp-edged end of the head of a mason's hammer.
  • transitive v. To draw, bend, or straighten, as metal, by blows with the peen of a hammer or sledge.

from The Century Dictionary and Cyclopedia

  • To treat by striking regularly all over with the peen of a hammer.
  • n. That end of a hammer-head or similar tool which terminates in an edge, or in a sharp, rounded cone-shaped, hemispherical, or otherwise specially modified point, as distinguished form the ordinary flat face. See also cuts under hammer.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the part of a hammerhead opposite the flat striking surface (may have various shapes)


Probably of Scandinavian origin.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Etymology uncertain. Possibly from Old French panne, pene, (whence Modern French panne "peen"); possibly from a Scandinavian source, compare dialectal Norwegian penn "peen" or Danish pind "peg". (Wiktionary)
From penis by shortening. (Wiktionary)



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  • That makes sense. OED lists zillions of spellings, but it does define peen as "end of a hammer head opposite the face; (formerly) spec. the sharp or thin end." So we can both be correct. :-)

    April 8, 2008

  • That's quite possible; it's years since my dad taught me all this stuff. And the thing that makes me think you're right is that one of the hammers was the "ball pein" hammer (yes, different spelling), which had a rounded, mushroomy striking surface opposite the regular flat one. And then there was the "claw hammer", which was much better at removing nails. I have probably been misled by the name of the ball pein hammer into thinking that peins/peens are by definition rounded.

    April 7, 2008

  • Isn't it still called a peen, though, despite the shape?

    April 7, 2008

  • Unless it's a claw hammer…

    April 6, 2008

  • The end of a hammerhead opposite the face (striking side)

    February 23, 2007