clegg vs horse fly

clegg and horse fly both are nouns.

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

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

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

Other synonyms of clegg include cleg, horsefly.

clegg (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