range finder vs rangefinder

range finder and rangefinder both are nouns.

Word	Noun	Adjective	Verb	Adverb
range finder	Yes	No	No	No
rangefinder	Yes	No	No	No

As nouns, range finder and rangefinder are synonyms defined as:

range finder and rangefinder: a measuring instrument (acoustic or optical or electronic) for finding the distance of an object

range finder (noun)	rangefinder (noun)
a measuring instrument (acoustic or optical or electronic) for finding the distance of an object	a measuring instrument (acoustic or optical or electronic) for finding the distance of an object