/ ˈbaʊndri; NAmE / noun ( pl. -ies )
a real or imagined line that marks the limits or edges of sth and separates it from other things or places; a dividing line :
( BrE )
boundary changes / disputes
The fence marks the boundary between my property and hers.
Scientists continue to push back the boundaries of human knowledge.
the boundary between acceptable and unacceptable behaviour
➡ note at border
( in cricket ) a hit of the ball that crosses the boundary of the playing area and scores extra points
early 17th cent.: variant of dialect bounder , from bound boundary + -er , perhaps on the pattern of limitary .