kit vs first-aid kit

kit and first-aid kit both are nouns.

Word	Noun	Adjective	Verb	Adverb
kit	Yes	No	Yes	No
first-aid kit	Yes	No	No	No

As nouns, first-aid kit is a hyponym of kit; that is, first-aid kit is a word with a more specific, narrower meaning than kit:

kit: gear consisting of a set of articles or tools for a specified purpose
first-aid kit: kit consisting of a set of bandages and medicines for giving first aid

Other hyponyms of kit include carpenter's kit, tool kit, layette, mess kit, sewing kit.

kit (noun)	first-aid kit (noun)
young of any of various fur-bearing animals	kit consisting of a set of bandages and medicines for giving first aid
gear consisting of a set of articles or tools for a specified purpose
a case for containing a set of articles

kit (verb)	first-aid kit (verb)
supply with a set of articles or tools