# Definition:Line/Straight Line Segment

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## Definition

A **straight line segment** is a line segment which is straight.

In the words of Euclid:

*A straight line segment can be drawn joining any two points.*

(*The Elements*: Postulates: Euclid's Second Postulate)

Thus a definition for **straight line** which is frequently encountered is:

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

## Also known as

Some sources take straightness for granted, and refer to such as just a **line segment**.

## Sources

- 2008: David Nelson:
*The Penguin Dictionary of Mathematics*(4th ed.) ... (previous) ... (next): Entry:**line segment** - 2014: Christopher Clapham and James Nicholson:
*The Concise Oxford Dictionary of Mathematics*(5th ed.) ... (previous) ... (next): Entry:**line segment**