1. a semicircular instrument used for measuring and drawing angles

Examples

• The student used a protractor to measure the 45-degree angle.
• Draw a 120-degree angle using your protractor and pencil.
• The geometry kit included a ruler, compass, and protractor.
• She placed the protractor’s center point on the vertex of the angle.
• The protractor showed that the angle measured exactly 90 degrees.
• Teachers often require students to bring a protractor to math class.