n.
- A line serving as a basis, as for measurement, calculation, or location.
- A measurement, calculation, or location used as a basis for comparison.
- Baseball. The base path.
- Sports.
- The boundary line at either end of a court, as in basketball or tennis.
- The area near this boundary line: made a basket from the base line.
- A style of play in tennis in which the player remains near the base line and rarely approaches the net.












