woodlouse vs wood louse

woodlouse and wood louse both are nouns.

Word	Noun	Adjective	Verb	Adverb
woodlouse	Yes	No	No	No
wood louse	Yes	No	No	No

As nouns, woodlouse and wood louse are synonyms defined as:

woodlouse and wood louse: any of various small terrestrial isopods having a flat elliptical segmented body; found in damp habitats

Other synonyms of woodlouse include slater.

woodlouse (noun)	wood louse (noun)
any of various small terrestrial isopods having a flat elliptical segmented body; found in damp habitats	any of various small terrestrial isopods having a flat elliptical segmented body; found in damp habitats