late 14c., pretenden, "to profess, put forward as a statement or assertion, maintain" (a claim, etc.), "to direct (one's) efforts," from Old French pretendre "to lay claim," from Latin praetendere "stretch in front, spread before, put forward; put forward as an excuse, allege," from prae "before" (see pre-) + tendere "to stretch" (from PIE root *ten- "to stretch").
Main modern sense of "feign, use as a pretext, put forward a false claim" is recorded from c. 1400; the older sense of simply "lay claim to" is behind the royal pretenders (1690s) in English history (see pretender). Meaning "to play, make believe" is recorded from 1865. In 17c. pretend also could mean "make a suit of marriage for," from a sense in French. Related: Pretended; pretending.