decaf vs coffee

decaf and coffee both are nouns.

Word	Noun	Adjective	Verb	Adverb
decaf	Yes	No	No	No
coffee	Yes	No	No	No

As nouns, coffee is a hypernym of decaf; that is, coffee is a word with a broader meaning than decaf:

Other hypernyms of decaf include java.

decaf (noun)	coffee (noun)
coffee with the caffeine removed	a medium brown to dark-brown color
	a beverage consisting of an infusion of ground coffee beans
	a seed of the coffee tree; ground to make coffee
	any of several small trees and shrubs native to the tropical Old World yielding coffee beans