A line is breadthless length.

The extremities of a line are points.

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

A plane surface is a surface which lies evenly with the straight lines on itself.

A plane angle is the inclination to one another of two lines in a plane which meet one another and do not lie in a straight line.

And when the lines containing the angle are straight, the angle is called rectilineal.

Parallel straight lines are straight lines which, being in the same plane and being produced indefinitely in both directions, do not meet one another in either direction.

To draw a straight line from any point to any point.

To produce a finite straight line continuously in a straight line.

That, if a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, meet on that side on which are the angles less than the two right angles.

To place at a given point (as an extremity) a straight line equal to a given straight line.

Given two unequal straight lines, to cut off from the greater a straight line equal to the less.