(n.) That which indicates or fixes a limit or extent, or marks a bound, as of a territory; a bounding or separating line; a real or imaginary limit.

Thule Ultima Thule ankle articulation balustrade barrier bisector bitter end border line bordering borderline borders bottom dollar bound boundary condition boundary line bounding bounds bourn break boundary breakoff point butt butt end caesura caudal ceiling cervix circumscription clinch closure coastal colon comma compass conclusive confine confinement confines connecting link connecting rod connection continence coupling cutoff cutoff point deadline definitive delimitation determinant determinative determining diameter discipline divider division line dovetail elbow embrace end endmost equator eventual extreme extremity fag end farthest farthest bound fence final finish floor fringing frontier frontiers gliding joint halfway mark hedge high-water mark hinge hinged joint hip interface join joining joint jumping-off place juncture knee knuckle last limbic limen liminal limit limitation limiting limiting factor limits line line of demarcation link littoral low-water mark lower limit march marginal mark mete miter moderation mortise neck nib partition pause perimeter period pivot pivot joint point polar pole precincts prescription proscription purlieus qualification rabbet rail railing restrain restriction rimming scarf seam semicolon shoulder skirting start starting line starting point stitch stone wall stop stub stump suture symphysis tag tag end tail tail end target date term terminal terminal date terminating terminative terminus threshold tie rod time allotment tip toggle toggle joint ultimate union upper limit wall weld wrist