definition of
boundary

[1] #1 boundary n. [bound, bounds] the line or plane indicating the limit or extent of something. wn

[2] #2 boundary n. [edge, bound] a line determining the limits of an area. wn

[3] #3 boundary n. [limit, bound] the greatest possible degree of something; "what he did was beyond the bounds of acceptable behavior"; "to the limit of his ability". wn