SkillsUSA Carpentry Practice Test

Plumb describes vertical alignment. A line or edge that is perfectly vertical is plumb because it follows gravity straight up and down. In practice, you use a plumb line (a weight on a string) or a vertical laser to check or establish that vertical reference. Level is about horizontal orientation (though some levels have vertical use), square ensures right angles, and true speaks to straightness or accuracy but not specifically vertical alignment. So the vertically exact line or edge is plumb.