acute is an adjective with multiple meanings:
1. (of a bad, difficult, or unwelcome situation) very serious or severe
2. (of an illness) of short duration but typically severe
3. having or showing a perceptive understanding or insight; shrewd
4. (of a physical sense or faculty) highly developed; keen
5. (in geometry) of an angle, less than 90°
6. (phonetics) denoting a sound that is sharp or shrill