Count
The beats in the measure are called counts, from the practice of counting the time.
Counterpoint [from Latin contra-punctus, against the point). Notes were originally called points, hence when another set of points were added above or below the points of the theme, they were called counterpoints.
In modern use counterpoint may be defined as the art of making two or more parts move together with such freedom that they seem to be independent, each one with a design of its own.