- any of the four angles formed on the inside of two straight lines when crossed by a transversal
- the angle formed inside a polygon by two adjacent sides
- Any of the four angles formed between two straight lines intersected by a third straight line.
- An angle formed inside a polygon by two adjacent sides.
Angles 3, 4, 5, and 6 are interior angles. Angles 3 and 6 are alternate interior angles, as are angles 4 and 5.
(plural interior angles)
- (geometry) The inner angle between two sides of a polygon.