truncheon (n.)

c. 1300, "shaft of a spear," also "short stick, cudgel," from Old North French tronchon, Old French tronchon (11c., Modern French tronçon) "a piece cut off, thick stick, stump," from Vulgar Latin *truncionem (nominative *truncio), from Latin truncus "trunk of a tree" (see trunk (n.1)). Meaning "staff as a symbol of office" is recorded from 1570s; sense of "policeman's club" is recorded from 1816.