necessity vs thing

necessity and thing both are nouns.

Word	Noun	Adjective	Verb	Adverb
necessity	Yes	No	No	No
thing	Yes	No	No	No

As nouns, thing is a hypernym of necessity; that is, thing is a word with a broader meaning than necessity:

necessity (noun)	thing (noun)
anything indispensable	a separate and self-contained entity
the condition of being essential or indispensable	an action
	an artifact
	an entity that is not named specifically
	any attribute or quality considered as having its own existence
	a special abstraction
	a special objective
	a vaguely specified concern
	a statement regarded as an object
	an event
	a persistent illogical feeling of desire or aversion
	a special situation