What's the "een" in Halloween?
"an animal resembling a serpent, with legs added to it" [Johnson], late 14c., lusarde, from Anglo-French lusard, Old French laisarde "lizard" (Modern French lézard), from Latin lacertus (fem. lacerta) "lizard," of unknown origin, perhaps from PIE root *leq- "to bend, twist" [Klein].
Only in Lev. 11:30, as rendering of Hebrew _letaah_, so called from its "hiding." Supposed to be the Lacerta gecko or fan-foot lizard, from the toes of which poison exudes. (See CHAMELEON.)