pliant (adj.)
late 14c., from Old French ploiant "bending, supple; compliant, fickle," as a noun, "turncoat" (13c.), present participle of ploier "to bend," from Latin plicare "to fold, lay" (from PIE root *plek- "to plait"). Figurative sense of "easily influenced" is from c. 1400. Related: Pliancy.