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[truhn-yuh n] /ˈtrʌn yən/
either of the two cylindrical projections on a cannon, one on each side for supporting the cannon on its carriage.
any of various similar supports for machinery.
Origin of trunnion
1615-25; < French trognon trunk, stump, core (of fruit)
Related forms
trunnioned, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for trunnion
  • He described three types of bascule structures: trunnion, rolling lift and roller bearing.
  • Inspect swashplate trunnion bearings for wear and security.
  • The bridge problem involves a crack in a huge steel axle, or trunnion, at the north end of the northbound lift span.
  • It is a simple trunnion with a concrete counterweight set underneath the tail end.
British Dictionary definitions for trunnion


one of a pair of coaxial projections attached to opposite sides of a container, cannon, etc, to provide a support about which it can turn in a vertical
the structure supporting such a projection
Derived Forms
trunnioned, adjective
Word Origin
C17: from Old French trognon trunk
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for trunnion

"either of two round projections of a cannon," 1620s, from French trognon "core of fruit, stump, tree trunk," from Middle French troignon (14c.), probably, from Latin truncus (see trunk).

Online Etymology Dictionary, © 2010 Douglas Harper
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