noun

• The dividing line or location between two areas.
• (figurative, 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).
• (cricket) An edge or line marking an edge of the playing field.
• (cricket) 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.
• (topology) (of a set) The set of points in the closure of a set S, not belonging to the interior of that set.