"to steal in small quantities" (intrans.); "to steal or gain by petty theft" (trans.), 1540s, from pilfer (n.) "spoils, booty," c. 1400, from Old French pelfre "booty, spoils" (11c.), a word of unknown origin, possibly related to pelf. Related: Pilfered; pilfering. Pulfrour "a thief" is attested from mid-14c., implying earlier use.