Meaning

noun large swift fly the female of which sucks blood of various animals

originFrom Middle English clege, from Old Norse kleggi. Cognate with Norwegian Nynorsk klegg. Possibly ultimately from Proto-Indo-European *glōgʰ-s (“point”); compare Ancient Greek γλωχίς (glōkhís, “barb”).

Etymology from Wiktionary, CC BY-SA 3.0