appetizer vs cocktail

appetizer and cocktail both are nouns.

Word	Noun	Adjective	Verb	Adverb
appetizer	Yes	No	No	No
cocktail	Yes	No	No	No

As nouns, cocktail is a hyponym of appetizer; that is, cocktail is a word with a more specific, narrower meaning than appetizer:

appetizer: food or drink to stimulate the appetite (usually served before a meal or as the first course)
cocktail: an appetizer served as a first course at a meal

Other hyponyms of appetizer include antipasto, canape, hors d'oeuvre, crudites.

appetizer (noun)	cocktail (noun)
food or drink to stimulate the appetite (usually served before a meal or as the first course)	a short mixed drink
	an appetizer served as a first course at a meal