An acute angle is an angle smaller than a square corner. Measure the acute angle, an acute angle at the top, three acute angles.
It is under ninety degrees, and a triangle can have three of them while it can never have two of anything larger. The acute in it is the Latin for sharp, which is exactly what such a corner looks like.
1nounacute angleAn angle smaller than a square corner.
“The attic roof slopes down to meet the floor at an acute angle, so you can't stand near the edges.”
acute angle is an angle.
Practised in Light & Shadow, Shapes & Lines