Definition:Line/Straight Line

Definition

In the words of Euclid:

A straight line is a line which lies evenly with the points on itself.

Also defined as

An alternative definition for straight line which is frequently encountered is:

A straight line is the shortest distance between two points.

This is all very well but it assumes that the line in question terminates at two particular endpoints.

However, this is a perfectly valid definition of the concept of a straight line segment.