Border and Extremity

Border noun - The line or relatively narrow space that marks the outer limit of something.

Extremity is a synonym for border in end topic. In some cases you can use "Extremity" instead a noun "Border", when it comes to topics like boundary, margin.

Nearby Words: borderline, bordered, bordering, borderland, borderless

Extremity noun - A time or state of affairs requiring prompt or decisive action.

Border is a synonym for extremity in limit topic. You can use "Border" instead a noun "Extremity", if it concerns topics such as end, boundary, ultimate.

Nearby Words: extreme, extremely, extremist, extremism, extremeness