n.[C]

1. 统治者；管理者；支配者
   She was then ruler of Egypt.

   她当时是埃及的统治者。

2. 划线人；划线机
3. 尺，直尺；划线板
   The child used a ruler to draw straight lines.

   这孩子用一把直尺划直线。

n.

1. a person or agent exercising government or control.
2. a straight-edged strip of rigid material, marked at regular intervals and used to draw straight lines or measure distances.