rebec (n.)

small medieval three-stringed musical instrument with a pear-shaped sound box, played with a bow, early 15c., rebekke, from Old French rebec (15c.), an unexplained alteration (perhaps somehow influenced by bec "beak") of ribabe (13c.), which is ultimately from Arabic rebab.

Compare Old Provençal rebec, also, with random alterations, Middle English ribibe (c. 1400), ribible (early 14c.), Italian ribeca, ribebla, Portuguese arrabil, Spanish rabel. The same word also was used disparagingly for "old woman, crone," but the connection is unclear and it might involve the name Rebecca.