/bays"luyn'/ , n. Also, base line .
1. Baseball. the area between bases within which a base runner must keep when running from one base to another.
2. Tennis. the line at each end of a tennis court, parallel to the net, that marks the in-bounds limit of play.
3. (in perspective drawing) a horizontal line in the immediate foreground formed by the intersection of the ground plane and the picture plane.
4. a basic standard or level; guideline: to establish a baseline for future studies.
5. a specific value or values that can serve as a comparison or control.
6. Typography. the imaginary line on which the bottoms of primary letters align.
7. Survey. See under triangulation (def. 1).
8. Electronics. a horizontal or vertical line formed on the face of a cathode-ray tube by the sweep of the scanning dot.
9. Naval Archit. a line on the body plan or sheer plan of a hull, representing a horizontal reference plane for vertical dimensions.
adj.
10. basic or essential.
[ 1740-50; BASE 1 + LINE 1 ]