- either of two projecting pivots, located on each side of a cannon or its mount, by which the muzzle is raised and lowered
- either of any similar pair of pins or pivots
Origin of trunnionFrench trognon, a stump, trunk
A pin or gudgeon, especially either of two small cylindrical projections on a cannon forming an axis on which it pivots.
Origin of trunnionFrench trognon stump
From French trognon (“core, stump").