- The definition of a ruler is a strip of wood, plastic or metal used for measuring, or a leader.
- An example of a ruler is a wooden tool used to measure the length of a piece of paper.
- An example of a ruler is a king.
- a person or thing that rules or governs
- a thin strip of wood, metal, etc. with a straight edge and markings in whole and fractional units of length, as inches or centimeters, used in drawing straight lines, measuring length, etc.
- a person or device that rules lines on paper, etc.
- One, such as a monarch or dictator, that rules or governs.
- A straightedged strip, as of wood or metal, for drawing straight lines and measuring lengths. Also called rule.
rule + -er.