priming coat vs couch

priming coat and couch both are nouns.

Word	Noun	Adjective	Verb	Adverb
priming coat	Yes	No	No	No
couch	Yes	No	Yes	No

As nouns, couch is a hyponym of priming coat; that is, couch is a word with a more specific, narrower meaning than priming coat:

priming coat: the first or preliminary coat of paint or size applied to a surface
couch: a flat coat of paint or varnish used by artists as a primer

priming coat (noun)	couch (noun)
the first or preliminary coat of paint or size applied to a surface	an upholstered seat for more than one person
	a narrow bed on which a patient lies during psychiatric or psychoanalytic treatment
	a flat coat of paint or varnish used by artists as a primer

priming coat (verb)	couch (verb)
	formulate in a particular style or language