Definition of cotter pin in English:

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cotter pin

Pronunciation: /ˈkɒtə pɪn/
(also cotter)


1A metal pin used to fasten two parts of a mechanism together.
Example sentences
  • She slid the cotter pin back through the nut and bolt and screwed the grease cap back on.
  • A cotter pin acts a safety measure to prevent the arm from sliding off the stub.
  • The cotter pin missed the male spline on the flap motor.
1.1A split pin that is opened out after being passed through a hole.


Mid 17th century: of unknown origin.

For editors and proofreaders

Line breaks: cot¦ter pin

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