Acute means sharp — sharp enough to hurt, or sharp enough to catch what everyone else misses. An acute pain under the ribs, an acute shortage of beds, an acute sense of smell that finds the gas leak before anyone has noticed a thing.
In medicine it means something narrower, and this is the one to learn: an acute illness comes on fast and does not last long, set against a chronic one that goes on for years. Acute appendicitis is sudden; chronic back pain is permanent. In geometry an acute angle is smaller than ninety degrees, and the mark over the e in café is an acute accent. The adverb is acutely, and it sits well in front of feelings: acutely aware, acutely embarrassed. Careful — an acute case is a sudden one, and sudden is not the same as bad.
1adjectiveacuteSevere and sharp — of pain, a shortage, embarrassment or need.
“There is an acute shortage of nurses in the region.”
2adjectiveillnessOf an illness: starting suddenly and lasting a short time.
“He was admitted with acute pneumonia and home within the week.”
3adjectivekeenQuick to notice things; very sensitive.
“Dogs have an acute sense of hearing.”
synonyms: keen, sharp
4adjectiveangleOf an angle: less than ninety degrees.
“The roof meets the wall at an acute angle.”
Too few real examples of this word to estimate which sense is commonest.
The Latin acus is a needle. Acute pain is a needle going in, not a dull bruise spreading — sharp, sudden, and exact.
hooks ontoneedle
Acute is Latin acūtus, sharpened, the participle of acuō, to whet or make pointed, from acus, a needle. English took it in the Middle Ages as a word for fevers that struck suddenly and burned out fast, so the medical sense came first. The Proto-Indo-European root under it all, *h₂eḱ-, is the sharp-edged root that runs beneath a whole family of pointed words.
Proto-Indo-European
*h₂eḱ-
Latin
acūta
Middle English
acute — of a disease or fever: starting suddenly and lasting for a short time; of a humour: irritating, sharp
English, today
acute
Built from
From Late Middle English acute (“of a disease or fever: starting suddenly and lasting for a short time; of a humour: irritating, sharp”), from Latin acūta, from acūtus (“sharp, sharpened”), perfect passive participle of acuō (“to make pointed, sharpen, whet”), from acus (“needle, pin”). The word is cognate to a doublet of ague. As regards the noun, which is derived from the verb, compare Middle English acūte (“severe but short-lived fever; of blood: corrosiveness, sharpness; musical note of high pitch”).
Etymology from Wiktionary, CC BY-SA