A (fine) dividing line or boundary line. to cut (to) a thread (between): to strike the exact line of division, to ‘draw the line’. Obsolete.

One who or that which divides; something that separates or forms the boundary between two regions, etc.; in Arithmetic = divisor, n.

? A partition or boundary. Obsolete.

(a) a notional or imaginary line; (Geometry) = line, n.2 9a; (b) Geometry the single line at infinity that is regarded as containing all the ideal…

In North American, Australian usage, etc.: A ridge or line of high ground forming the division between two river valleys or systems; a watershed…

The strip of land along the border between two countries or districts; a frontier-line; often figurative, the boundary between areas, classes, etc.