mid-14c., "to put to death by nailing or otherwise affixing to a cross," from Old French crucifer crucefiier (12c., Modern French crucifier), from Vulgar Latin *crucificare, from Late Latin crucifigere "to fasten to a cross," from cruci, dative of Latin crux "cross" (see crux) + figere "to fasten, fix" (from PIE root *dheigw- "to stick, fix").
An ancient mode of capital punishment considered especially ignominious by the Romans and Greeks and reserved in general for slaves and highway robbers. In scripture, "subdue, mortify" (the flesh, etc.), early 14c. Figurative sense of "to torment" is from 1620s. Related: Crucified; crucifying.