weightlift vs weight-lift

weightlift is a noun but weight-lift is not a noun.

Word	Noun	Adjective	Verb	Adverb
weightlift	Yes	No	Yes	No
weight-lift	No	No	Yes	No

As verbs, weightlift and weight-lift are synonyms defined as:

Other synonyms of weightlift include press.

weightlift (noun)	weight-lift (noun)
bodybuilding by exercise that involves lifting weights

weightlift (verb)	weight-lift (verb)
lift weights	lift weights