Acute, from the Latin, suggests the sharpness of the needle's point; keen, from the Saxon, the sharpness of the cutting edge. Astute, from the Latin, with the original sense of cunning has come to have a meaning that combines the sense of acute or keen with that of sagacious.

J. C. Fernald, English Synonyms and Antonyms (1914)

Example sentences

critical I can't understand why you are so critical of him.
urgent Being less urgent, this plan is lower in priority.
perceptive Too much alcohol paralyzes our perceptive powers.
soft The bread is cutting badly because it's very soft.
intense She was as intense in her hatreds as in her loves.

Popularity over time

Word	1850 → 2019	Trend
acute		steady
critical		rising
urgent		falling
perceptive		falling
soft		rising

Use in printed books, per decade from 1850 to 2019.

By length

4 letters: high¹, fast¹, soft¹, keen¹, dire¹
5 letters: clear¹, quick¹, sharp¹, rapid²
6 letters: strong¹, severe², bright¹, sudden², urgent², piping², astute², acuate
7 letters: violent³, pointed², intense², instant², pungent²
8 letters: critical³, powerful³, pressing², piercing², poignant², emergent³, incisive³, peracute, preacute
9 letters: exquisite³, acuminate, sagacious
10 letters: perceptive³
11 letters: penetrating⁴, distressing³
14 letters: discriminating⁵

The small number after each word is its number of syllables (rapid² = 2 syllables).

In other languages

Français: aigu
Español: agudo
Deutsch: schrill
Català: agut