Bar

Definition (Bar): In English, bar-line or, more usually, measure. 

Definition (Bar-line): The vertical line used to indicate the beginning and end of a measure.

Credit: Harvard Dictionary of Music

Definition: American term, equivalent to the English term "bar ", signifying the smallest metrical divisions of a composition, containing a fixed number of beats , marked off by vertical lines on the staff.

Source: OnMusic Dictionary 

Measure, Musical measure