acute

a mark (') placed above a vowel to indicate pronunciation

having or experiencing a rapid onset and short but severe course; "acute appendicitis"; "the acute phase of the illness"; "acute patients"

extremely sharp or intense; "acute pain"; "felt acute annoyance"; "intense itching and burning"

having or demonstrating ability to recognize or draw fine distinctions; "an acute observer of politics and politicians"; "incisive comments"; "icy knifelike reasoning"; "as sharp and incisive as the stroke of a fang"; "penetrating insight"; "frequent penetrative observations"

of an angle; less than 90 degrees

ending in a sharp point

of critical importance and consequence; "an acute (or critical) lack of research funds"