ruler
noun [ C ] uk/ˈruː.lər/ us/ˈruː.lɚ/
(LEADER)
C1 统治者
the leader of a country
The country was without a ruler after the queen died. 女王死后，这个国家陷入了无人统治的状态。
(FOR DRAWING)
A2 (old-fashioned or formal rule)直尺；尺子
a long, narrow, flat piece of plastic, metal, or wood with straight edges where centimetres or inches, or both are printed. It is used for measuring things and for drawing straight lines.