acute vs critical

acute is a noun but critical is not a noun.

Word	Noun	Adjective	Verb	Adverb
acute	Yes	Yes	No	No
critical	No	Yes	No	No

acute (noun)	critical (noun)
a mark placed above a vowel to indicate pronunciation

acute (adjective)	critical (adjective)
having or experiencing a rapid onset and short but severe course	marked by a tendency to find and call attention to errors and flaws
of an angle; less than 90 degrees	characterized by careful evaluation and judgment
of critical importance and consequence	being in or verging on a state of crisis or emergency
having or demonstrating ability to recognize or draw fine distinctions	at or of a point at which a property or phenomenon suffers an abrupt change especially having enough mass to sustain a chain reaction
ending in a sharp point	of or involving or characteristic of critics or criticism
extremely sharp or severe	forming or having the nature of a turning point or crisis
	urgently needed; absolutely necessary