righthander vs right hander

righthander and right hander both are nouns.

Word	Noun	Adjective	Verb	Adverb
righthander	Yes	No	No	No
right hander	Yes	No	No	No

As nouns, righthander and right hander are synonyms defined as:

righthander and right hander: a person who uses the right hand more skillfully than the left

Other synonyms of righthander include right-hander.

righthander (noun)	right hander (noun)
a person who uses the right hand more skillfully than the left	a person who uses the right hand more skillfully than the left