pan roast vs roast

pan roast is not a noun while roast is a noun.

Word	Noun	Adjective	Verb	Adverb
pan roast	No	No	Yes	No
roast	Yes	Yes	Yes	No

As verbs, roast is a hypernym of pan roast; that is, roast is a word with a broader meaning than pan roast:

pan roast (noun)	roast (noun)
	negative criticism
	a piece of meat roasted or for roasting and of a size for slicing into more than one portion

pan roast (adjective)	roast (adjective)
	(meat) cooked by dry heat in an oven

pan roast (verb)	roast (verb)
roast in a pan	cook with dry heat, usually in an oven
	subject to laughter or ridicule