from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A line parallel to one end of a billiard table, from behind which opening shots with the cue ball are made.
from the GNU version of the Collaborative International Dictionary of English
- n. a line across a billiard table near one end, marking a limit within which the cue balls are placed in beginning a game; also, a line around the table, parallel to the sides, used in playing a particular game, called the balk line game.
Sorry, no etymologies found.