Acute most commonly indicates intensification, sometimes rapid, of a situation demanding notice and showing signs of some definite resolution.
- intimately associated with Indian affairs was the pressing question of defense . . . Pontiac’s rebellion made the issue acute
—Morison & Commager
- when the food shortage became acute in New Haven, the junior class of Yale College was moved to Glastonbury
—Amer. Guide Series: Conn.
Critical may describe an approach to a crisis or turning point and may imply an imminent outcome or resolution.
- the war has reached a new critical phase . . . we have moved into active and continuing battle
- the critical lack of rubber in the last war was finally beaten by the development of synthetic rubber plants capable of turning out 1,000,000 tons a year
—Collier’s Yr. Bk.
Crucial applies to an actual crisis situation, often one viewed with fear, worry, or suspense, and implies a speedily ensuing decisive or définitive outcome.
- a continuous evolution, punctuated by the sudden flaming or flowering of a crucial moment now and then
- the next few months are crucial. What we do now will affect our American way of life for decades to come