late 15c., from Latin truncatus "cut off," past participle of truncare "to maim, mutilate, cut off," from truncus "maimed, mutilated," also "trunk of a tree, trunk of the body," of uncertain origin, probably originally "mutilated, cut off," and perhaps from PIE root *tere- (2) "cross over, pass through, overcome." Related: Truncated; truncating.

early 15c., from Late Latin truncationem (nominative truncatio), noun of action from past-participle stem of truncare (see truncate).