2. Sylph,salamander,undine ( nymph ), gnome were imaginary beings inhabiting the four elements once believed to make up the physical world. All except the gnomes were female. Sylphs dwelt in the air and were light, dainty, and airy beings. Salamanders dwelt in fire: “a salamander that … lives in the midst of flames” (Addison). Undines were water spirits: By marrying a man, an undine could acquire a mortal soul. (They were also called nymphs, though nymphs were ordinarily minor divinities of nature who dwelt in woods, hills, and meadows as well as in waters.) Gnomes were little old men or dwarfs, dwelling in the earth: ugly enough to be king of the gnomes.
1650s, from Modern Latin sylphes (plural), coined 16c. by Paracelsus (1493-1541), originally referring to any race of spirits inhabiting the air, described as being mortal but lacking a soul. Paracelsus' word seems to be an arbitrary coinage, but perhaps it holds a suggestion of Latin sylva and Greek nymph. The meaning "slender, graceful girl" first recorded 1838, on the notion of "light, airy movements." Silphid (1670s) are the younger or smaller variety, from French sylphide (1670s).