/ ˈruːlə(r); NAmE / noun
1.
a person who rules or governs
2.
a straight strip of wood, plastic or metal, marked in centimetres or inches, used for measuring or for drawing straight lines
RULER
Meaning of RULER in English
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005