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Webster 1913 Edition

(-?r)

Noun.

One who, or that which, crushes.

Crusher gauge

an instrument for measuring the explosive force of gunpowder, etc., by its effect in compressing a piece of metal.

crusher ‎(plural crushers)

Someone or something that crushes.
A machine designed to crush rocks.
(slang) A policeman.
- 1977, John Le Carré, The Honourable Schoolboy, Folio Society 2010, p. 110:
  Back in the lobby he bought a copy of Time but didn't like the way the plain-clothes crushers looked at him, and left.