cook out vs barbecue

cook out is not a noun while barbecue is a noun.

Word	Noun	Adjective	Verb	Adverb
cook out	No	No	Yes	No
barbecue	Yes	No	Yes	No

As verbs, cook out and barbecue are synonyms defined as:

Other synonyms of cook out include barbeque.

cook out (noun)	barbecue (noun)
	a rack to hold meat for cooking over hot charcoal usually out of doors
	a cookout in which food is cooked over an open fire; especially a whole animal carcass roasted on a spit
	meat that has been barbecued or grilled in a highly seasoned sauce

cook out (verb)	barbecue (verb)
cook outdoors on a barbecue grill	cook outdoors on a barbecue grill