siren (n.) Look up siren at Dictionary.com
mid-14c., "sea nymph who by her singing lures sailors to their destruction," from Old French sereine, from Late Latin Sirena, from Latin Siren, from Greek Seiren ["Odyssey," xii.39 ff.], perhaps literally "binder," from seira "cord, rope."

Meaning "device that makes a warning sound" (on an ambulance, etc.) first recorded 1879, in reference to steamboats. Figurative sense of "one who sings sweetly and charms" is recorded from 1580s.