These words refer to the bounding line or outline of something. Edge refers to the thin line along one side of a thing: the edge of the table; the south edge of the terrace. Or it may refer to the line between two sides or planes: the edge of an axe. In either case the word refers to a line that does not circumscribe a figure but may form part of its perimeter. As such, it can refer to any sort of boundary: the ragged edge of the forest. Unqualified, however, the word often suggest a straight or sharp line: He tested the edge of the knife with one finger. Metaphorically, the word may indicate the shape line between two contrasting qualities or states or, particularly; the line delimiting an undesirable state: nations drifting closer to the edge of disaster.

Brink also indicates a line that is not circumscribing, but the word’s stress is on an abrupt division between high and low ground: the brink of the cliff; the brink of a valley. Verge once could refer literally either to a dividing or circumscribing line in as general a way as edge , but now it is almost completely limited to metaphorical uses. Here, it suggests the imminence or nearness of an abrupt shift to some other condition, good or bad: on the verge of succeeding at last; on the verge of a nervous breakdown. Brink functions similarly in a metaphorical way, except that it almost exclusively applies to the imminence of something undesirable: on the brink of war. It may also suggest speed, inevitability and possible destruction such as would be true in falling over a literal chasm: In international affairs, brinkmanship is the tactic of risking nuclear confrontation in the hope that one can stop short in time without plummeting headlong over the brink .

All the remaining words can refer to a circumscribing outline. Border and margin , furthermore, most often refer to plane figures. Border can indicate the area of such a figure that is nearest to its outside edges : They walked about the border of the park. The word can also refer to a circumscribing boundary that contrasts distinctly with what it encloses and thus sets off or frames the contained area: a black border round the portrait of the dead sovereign; a modest border of lawn round the house. In this sense, the word may imply an added, decorative edge : the lace border of her handkerchief. Boarder can, however, refer like edge to a dividing line, as in its common use for the boundary between two countries: the border between Canada and the United States. Margin emphasizes exclusively one aspect of border , pointing to the outer area circumscribing something, an area that is often distinct in appearance from what it encloses. Unlike border , however, margin more frequently refers to the emptiness, blankness or lack of decoration that sets off and surrounds something. Typescript looks best when at least an inch of margin is left on all four sides of the page. To this implication of space left unused can be added the notion of its being saved for an emergency: margin for error.

Rim and brim also refer to a circumscribing outline, in this case that of a circle. Rim refers most specifically to the open lip of a cylindrical or rounded shape: She tested the rim of the glass to see if it was chipped; on the rim of the volcano. Brim can refer to the same open lip, but is most often associated with a situation in which a container is completely filled: a teacup filled to the brim . This use extends to shapes that are not rounded: rail trucks filled to the brim with grain. But brim has at least one use where it functions more like border or margin: the brim of a hat.