"to emit soft, rapid sounds," late 14c. (implied in rustling), of uncertain origin, perhaps imitative (compare Middle Low German ruschen, Middle Dutch ruusscen, German rauschen "to rustle"). Related: Rustled; rustling. Meaning "steal" (especially cattle) first attested 1882, probably from earlier American English slang sense of "move about vigorously" (1844), perhaps a separate word, compounded from rush and hustle.
