In medicine, describing a disease as acute denotes that it is of recent onset; it occasionally denotes a short duration. In order to be an acute triangle, all three angles of a triangle must be less than 90°. These triangles can have very prickly personalities. For such a short and simple-looking word, acute has a rather bewildering range of meanings. It first entered the English language with a medical sense, referring to the sharpness or severity of a symptom. In medical terminology, acute describes a condition that comes on suddenly and typically lasts a short time. It’s one of the most common words you’ll encounter on medical charts, diagnosis labels, and doctor visit summaries. This disambiguation page lists articles associated with the title Acute. If an internal link incorrectly led you here, you may wish to change the link to point directly to the intended article. The simple definition of ACUTE is very serious or dangerous : requiring serious attention or action. ACUTE definition: sharp or severe in effect; intense. See examples of acute used in a sentence. acute adjective (EXTREME) If a bad situation is acute, it causes severe problems or damage: acute adjective (EXTREME) If a bad situation is acute, it causes severe problems or damage: In medicine, “acute” means sudden and short-lived — not severe. Learn how it differs from chronic conditions and why the distinction matters for your care.