Other forms: rulers
A ruler is the flat marked stick used for drawing straight lines and measuring. A thirty-centimetre ruler, use a ruler, a metal ruler.
School rulers are usually thirty centimetres and marked in both centimetres and inches. The other sense is somebody who governs a country: an absolute ruler, the rulers of the city. The two are the same word: to rule is both to govern and to draw a straight line, and the second sense came from the idea of laying down a straight standard. Note ruled paper, meaning paper with lines printed on it.
1nounrulerA flat marked stick for drawing lines and measuring.
“The ruler in that drawer has been snapped in half.”
2noungovernsSomebody who governs a country.
“The ruler at the time was about fourteen years old.”
ruler is a measuring stick, or a governor.
The word is rule plus -er, and the double meaning is in the Latin: regula meant a straight stick and a rule of conduct at once, from regere, to guide or govern. Regular, regime and royal are all the same root.
Middle English
reuler
English, today
ruler
From Middle English reuler; equivalent to rule + -er.
Etymology from Wiktionary, CC BY-SA