The dividing line or location between two areas.
(often in the plural) The bounds, confines, or limits between immaterial things (such as one’s comfort zone, privacy, or professional sphere and the realm beyond).
An edge or line marking an edge of the playing field.
An event whereby the ball is struck and either touches or passes over a boundary (with or without bouncing), usually resulting in an award of 4 (four) or 6 (six) runs respectively for the batting team.
(of a set) The set of points in the closure of a set S, not belonging to the interior of that set.