instillation vs intromission

instillation and intromission both are nouns.

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

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

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

Other hypernyms of instillation include insertion, introduction.

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