addition vs indefinite quantity

addition and indefinite quantity both are nouns.

Word	Noun	Adjective	Verb	Adverb
addition	Yes	No	No	No
indefinite quantity	Yes	No	No	No

As nouns, indefinite quantity is a hypernym of addition; that is, indefinite quantity is a word with a broader meaning than addition:

addition (noun)	indefinite quantity (noun)
the arithmetic operation of summing; calculating the sum of two or more numbers	an estimated quantity
the act of adding one thing to another
a component that is added to something to improve it
a suburban area laid out in streets and lots for a future residential area
something added to what you already have
a quantity that is added