bedbug vs bed bug

bedbug and bed bug both are nouns.

Word	Noun	Adjective	Verb	Adverb
bedbug	Yes	No	No	No
bed bug	Yes	No	No	No

As nouns, bedbug and bed bug are synonyms defined as:

bedbug and bed bug: bug of temperate regions that infests especially beds and feeds on human blood

Other synonyms of bedbug include chinch, Cimex lectularius.

bedbug (noun)	bed bug (noun)
bug of temperate regions that infests especially beds and feeds on human blood	bug of temperate regions that infests especially beds and feeds on human blood