boundary
Noun

The line or plane indicating the limit or extent of something (synset 108529331)
hypernym: extremity  the outermost or farthest region or pointhyponym:
 hairline  the natural margin formed by hair on the head
 frontier  an international boundary or the area (often fortified) immediately inside the boundary
 heliopause  the boundary marking the edge of the sun's influence; the boundary (roughly 100 AU from the sun) between the interplanetary medium and the interstellar medium; where the solar wind from the sun and the radiation from other stars meet
 border, borderline, boundary line, delimitation, mete  a line that indicates a boundary
 bourn, bourne  an archaic term for a boundary
 district line  the boundary between two districts
 county line  the boundary between two counties
 city line  the boundary of a city
 border, edge  the boundary of a surface
 end  a boundary marking the extremities of something
 demarcation, demarcation line, limit  the boundary of a specific area
 lineation, outline  the line that appears to bound an object
 surface  the extended twodimensional outer boundary of a threedimensional object
 shoreline  a boundary line between land and water
instance hyponym: rubicon  the boundary in ancient times between Italy and Gaul; Caesar's crossing it with his army in 49 BC was an act of war
 moho, mohorovicic discontinuity  the boundary between the Earth's crust and the underlying mantle

A line determining the limits of an area (synset 113926085)
hypernym: line  a length (straight or curved) without breadth or thickness; the trace of a moving pointhyponym:
 rim  the shape of a raised edge of a more or less circular object
 border, margin, perimeter  the boundary line or the area immediately inside the boundary
 fringe, outer boundary, periphery  the outside boundary or surface of something
 brink, threshold, verge  a region marking a boundary
 upper bound  (mathematics) a number equal to or greater than any other number in a given set
 lower bound  (mathematics) a number equal to or less than any other number in a given set
 thalweg  the middle of the chief navigable channel of a waterway that forms the boundary line between states

The greatest possible degree of something (synset 105131322)
"what he did was beyond the bounds of acceptable behavior"; "to the limit of his ability"hypernym: extent  the distance or area or volume over which something extendshyponym:
 knifeedge  a narrow boundary
 absoluteness, starkness, utterness  the quality of being complete or utter or extreme
 heat barrier, thermal barrier  a limit to high speed flight imposed by aerodynamic heating
 level best, maximum, utmost, uttermost  the greatest possible degree
 brink, verge  the limit beyond which something happens or changes
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