Acute Meaning Across Medicine, Math and Daily Speech

The main senses, numbered

1. In medicine: sudden onset, usually short course. "Acute appendicitis needs prompt surgery."
2. In geometry: less than 90 degrees. "Each corner of this triangle is an acute angle."
3. Of the senses or the mind: keen and sensitive. "Owls have acute hearing." "She gave an acute analysis of the budget."
4. Of a problem or feeling: severe and intense. "There is an acute shortage of nurses." "He felt acute embarrassment."
5. In language: the accent mark (´) placed over a letter, as in café.

If you want to define acute in a phrase that covers them all, "sharply focused or sharply felt" comes close.

Acute definition in medicine

Doctors call a condition acute when it starts quickly and, typically, lasts a fairly short time: a sprained ankle, a chest infection, a sudden asthma attack, food poisoning. On its own the label says nothing about danger. A mild cold is an acute illness, and so is a heart attack.

You will also meet the word in service names. Acute care refers to short-term hospital treatment for a sudden illness, injury or operation, and acute wards are where such patients go. Terms such as acute kidney injury or acute stress reaction describe conditions that develop over hours or days rather than months.

Acute vs chronic

A chronic condition can also have an acute flare, when symptoms suddenly worsen for a while. So a person with long-term asthma might have an acute attack. The words describe time, not seriousness, which is the single most common mistake people make with them. For another medical pair often misread, see benign and malignant.

Acute angles in math

In geometry, an acute angle measures more than 0 and less than 90 degrees. A right angle is exactly 90, and an obtuse angle is between 90 and 180. A triangle whose three angles are all acute is called an acute triangle; an equilateral triangle, with three 60 degree angles, is one.

The word perpendicular, for lines meeting at a right angle, is the natural next term to learn.

Acute meaning in everyday use, with examples

• Dogs have an acute sense of smell, far beyond ours.
• The town faces an acute housing shortage after the factory expanded.
• She is acutely aware that her team is tired.
• His review of the novel was short but acute.
• I had acute toothache all weekend and could not sleep.

Pairings worth knowing: acute shortage, acute pain, acute crisis, acute observer, acutely aware, acutely embarrassed. The adverb acutely almost always means "very strongly," and "acutely aware" is one of its most frequent uses.

From a Latin word for sharpening

English has used acute since the late 1300s, first for fevers and illnesses that came quickly to a crisis. It goes back to Latin acutus, "sharpened, pointed," the past participle of acuere, "to sharpen." The same root shows up in acupuncture (needle pricking) and acumen (sharpness of mind).

A fun link: the everyday word cute started out in the 1700s as a clipped form of acute, meaning clever or sharp. Its sense of "sweet and attractive" came later.

Mistakes to avoid

• Acute is not "very serious." In medicine it means sudden. Say "severe" if you mean bad.
• Acute vs obtuse. Obtuse angles are wide; an obtuse person is slow to understand. They are opposites in both geometry and wit.
• Spelling. One c, one t: a-c-u-t-e. Not "accute."

More terms from medicine and math sit together on our science and ideas hub, which is a good next stop for the full definition of acute in context.