mid-14c., in classical mythology, "sea nymph who by her singing lures sailors to their destruction," from Old French sereine (12c., Modern French sirène) and directly from Latin Siren (Late Latin Sirena), from Greek Seiren ["Odyssey," xii.39 ff.], one of the Seirēnes, the mythical sisters who enticed sailors to their deaths with their songs, also in Greek "a deceitful woman," perhaps literally "binder, entangler," from seira "cord, rope."
The meaning "mechanical device that makes a warning sound" is recorded by 1879, in reference to steamboats, perhaps from similar use of the French word. It later was extended to such devices for air raids, factory shifts, police cars, etc. In 20c. this use was sometimes spelled sireen.
The figurative sense of "one who sings sweetly and charms and allures" is recorded from 1580s. The classical descriptions of them were mangled in medieval translations and glosses, resulting in odd notions of their appearance. In English they generally were portrayed as harpies, but "In early use frequently confused with the mermaid" [OED]. Also in Middle English the name of a imaginary species of flying serpents, based on glossary explanations of Latin sirenes in Vulgate (Isaiah xiii.22).
For adjectives the Elizabethans tried sirenean, sirenian, sirenic, sirenical, sireny. Ruskin used sirenic, so it might be called the survivor.