lamia (n.) Look up lamia at Dictionary.com
late 14c., from Latin lamia, from Greek lamia "female vampire," literally "swallower, lecher," from laimos "throat, gullet." Probably cognate with Latin lemures "spirits of the dead" (see lemur). Used in early translations of the Bible for screech owls and sea monsters. Sometimes also, apparently, mermaids.
Also kynde erreþ in som beestes wondirliche j-schape, as it fareþ in a beest þat hatte lamia, þat haþ an heed as a mayde & body as a grym fissche[;] whan þat best lamya may fynde ony man, first a flatereþ wiþ hym with a wommannes face and makeþ hym ligge by here while he may dure, & whanne he may noferþere suffice to here lecherye þanne he rendeþ hym and sleþ and eteþ hym. [John of Trevisa, translation of Bartholomew de Glanville's "De proprietatibus rerum," 1398]