Noun boundary has 3 senses
  1. boundary, bound, bounds - the line or plane indicating the limit or extent of something
    --1 is a kind of extremity
    --1 has particulars:
     hairline; frontier; heliopause; boundary line, border, borderline, delimitation, mete; bourn, bourne; district line; county line; city line; edge, border; end; limit, demarcation, demarcation line; outline, lineation; Rubicon; surface; shoreline
    Derived form: verb bound2
  2. boundary, edge, bound - a line determining the limits of an area
    --2 is a kind of line
    --2 has particulars:
     rim; margin, border, perimeter; periphery, fringe, outer boundary; brink, threshold, verge; upper bound; lower bound; thalweg
    Derived form: verb bound2
  3. limit, bounds, boundary - the greatest possible degree of something; "what he did was beyond the bounds of acceptable behavior"; "to the limit of his ability"
    --3 is a kind of extent
    --3 has particulars:
     knife-edge; thermal barrier, heat barrier; utmost, uttermost, maximum, level best; verge, brink