expelling vs activity

expelling and activity both are nouns.

Word	Noun	Adjective	Verb	Adverb
expelling	Yes	No	No	No
activity	Yes	No	No	No

As nouns, activity is a hypernym of expelling; that is, activity is a word with a broader meaning than expelling:

expelling: any of several bodily processes by which substances go out of the body
activity: an organic process that takes place in the body

Other hypernyms of expelling include bodily function, bodily process, body process.

expelling (noun)	activity (noun)
any of several bodily processes by which substances go out of the body	any specific behavior
	the trait of being active; moving or acting rapidly and energetically
	an organic process that takes place in the body
	a process existing in or produced by nature (rather than by the intent of human beings)
	the state of being active
	(chemistry) the capacity of a substance to take part in a chemical reaction