Meaning of trunnion

trun•nion

Pronunciation: (trun'yun), [key]
— n.
  1. either of the two cylindrical projections on a cannon, one on each side for supporting the cannon on its carriage.
  2. any of various similar supports for machinery.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.