S: (adj) acute (having or experiencing a rapid onset and short but severe course) "acute appendicitis"; "the acute phase of the illness"; "acute patients"
S: (adj) acute, intense (extremely sharp or severe) "acute pain"; "felt acute annoyance"; "intense itching and burning"
S: (adj) acute, discriminating, incisive, keen, knifelike, penetrating, penetrative, piercing, sharp (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"
S: (adj) acute (of an angle; less than 90 degrees)