instillment vs intromission

instillment and intromission both are nouns.

Word	Noun	Adjective	Verb	Adverb
instillment	Yes	No	No	No
intromission	Yes	No	No	No

As nouns, intromission is a hypernym of instillment; that is, intromission is a word with a broader meaning than instillment:

instillment: the introduction of a liquid (by pouring or injection) drop by drop
intromission: the act of putting one thing into another

Other hypernyms of instillment include insertion, introduction.

instillment (noun)	intromission (noun)
the introduction of a liquid (by pouring or injection) drop by drop	the act of putting one thing into another