acute

Extremely sharp or severe.

“acute pain”

“felt acute annoyance”

Having or demonstrating ability to recognize or draw fine distinctions.

“an acute observer of politics and politicians”

Ending in a sharp point.

Having or experiencing a rapid onset and short but severe course.

“acute appendicitis”

“the acute phase of the illness”

Of critical importance and consequence.

“an acute (or critical) lack of research funds”

A mark placed above a vowel to indicate pronunciation.

Of an angle; less than 90 degrees.