cleg vs horse fly

cleg and horse fly both are nouns.

Word	Noun	Adjective	Verb	Adverb
cleg	Yes	No	No	No
horse fly	Yes	No	No	No

As nouns, cleg and horse fly are synonyms defined as:

cleg and horse fly: large swift fly the female of which sucks blood of various animals

Other synonyms of cleg include clegg, horsefly.

cleg (noun)	horse fly (noun)
large swift fly the female of which sucks blood of various animals	large swift fly the female of which sucks blood of various animals