stop-leak vs stop leak

stop-leak and stop leak both are nouns.

Word	Noun	Adjective	Verb	Adverb
stop-leak	Yes	No	No	No
stop leak	Yes	No	No	No

As nouns, stop-leak and stop leak are synonyms defined as:

stop-leak and stop leak: a liquid that is added to the radiator to stop leaks.

stop-leak (noun)	stop leak (noun)
a liquid that is added to the radiator to stop leaks.	a liquid that is added to the radiator to stop leaks.