- a line serving as a base
- any starting or reference point, figure, amount, level, etc. with which others can be measured or compared
- Surveying a horizontal line measured with special accuracy to provide a base for survey by triangulation
- Baseball the unmarked lane, six feet (1.8 m) wide, between any two consecutive bases: a base runner who does not stay within this lane may, in certain situations, be called out by an umpire
- Basketball end line; esp., an area of the court just inside this line
- Tennis the line at the back at either end of the court
base linebase line
- It became the base-line of almost any rugged outdoor uniform.
- In 1784 the base-line of the first trigonometrical survey in England was laid down on the heath.
- P, Base-line of origin of the reflected mantle-flap from the side of the body.
- Along the base-line, and the lengths and directions of the offsets NB, PC, QD,.