acute (adj.)

late 14c., originally of fevers and diseases, "coming quickly to a crisis" (opposed to chronic), from Latin acutus "sharp, pointed," figuratively "shrill, penetrating; intelligent, cunning," past participle of acuere "to sharpen" (literal and figurative), from PIE root *ak- "be sharp, rise (out) to a point, pierce." Also used of humors (early 15c.). Meaning "ending in a sharp point" is from 1560s; sense of "sharp or penetrating in intellect" is from 1580s. Of feelings, pains, etc., "intense," 1727. As a noun, early 15c. of fevers; c. 1600 as "acute accent." Related: Acutely; acuteness.

Definitions of acute
acute (adj.)
having or experiencing a rapid onset and short but severe course;
acute appendicitis
the acute phase of the illness
acute patients
acute (adj.)
extremely sharp or severe;
felt acute annoyance
acute pain
Synonyms: intense
acute (adj.)
having or demonstrating ability to recognize or draw fine distinctions;
an acute observer of politics and politicians
Synonyms: discriminating / incisive / keen / knifelike / penetrating / penetrative / piercing / sharp
acute (adj.)
of an angle; less than 90 degrees;
acute (adj.)
ending in a sharp point;
Synonyms: acuate / sharp / needlelike
acute (adj.)
of critical importance and consequence;
an acute (or critical) lack of research funds
acute (n.)
a mark placed above a vowel to indicate pronunciation;
Synonyms: acute accent / ague