mid-14c., "change the form of" (transitive), from Old French transformer (14c.), from Latin transformare "change in shape, metamorphose," from trans- "across" (see trans-) + formare "to form" (see form (v.)). Intransitive sense "undergo a change of form" is from 1590s. Related: Transformed; transforming.[transform etymology, transform origin, 英语词源]