preparation vs boil down

preparation is a noun but boil down is not a noun.

Word	Noun	Adjective	Verb	Adverb
preparation	Yes	No	No	No
boil down	No	No	Yes	No

preparation (noun)	boil down (noun)
activity leading to skilled behavior
preparatory school work done outside school (especially at home)
the activity of putting or setting in order in advance of some act or purpose
the act of preparing something (as food) by the application of heat
the cognitive process of thinking about what you will do in the event of something happening
(music) a note that produces a dissonant chord is first heard in a consonant chord
the state of having been made ready or prepared for use or action (especially military action)
a substance prepared according to a formula

preparation (verb)	boil down (verb)
	cook until very little liquid is left
	be cooked until very little liquid is left
	be the essential element