n. (pl. -ies) 1 a line marking the limits of an area, territory, etc. (the fence is the boundary; boundary between liberty and licence). 2 Cricket a hit crossing the limits of the field, scoring 4 or 6 runs. boundary layer the fluid immediately surrounding an object that is immersed and moving. boundary rider Austral. & NZ a person employed to ride round the fences etc. of a cattle or sheep station and keep them in good order. boundary umpire (in Australian Rules) an umpire on the sidelines who signals when the ball is out.
[ dial. bounder f. BOUND(2) + -ER(1) perh. after limitary ]