Explanation:

- Acute: This word often refers to something severe or intense. In medical terms, it refers to a condition with a rapid onset and a short course.

- Option 1: Obtuse: This word generally means slow to understand or dull. It is the opposite of acute when referring to angles or intellectual sharpness.

- Option 2: Faithful: It means loyal or constant and has no direct relation to the intensity or severity that acute suggests.

- Option 3: Chronic: This term describes a condition lasting for a long time and not acute.

- Option 4: Dire: This signifies something extremely serious or urgent. It aligns most closely with the severity implied by acute.

- Correct Answer: Option 4: Dire