Definition of transversal in geometry

A transversal is a line that intersects two or more other lines on a plane at two or more distinct points.

In the figure above, the red line is a transversal.

• A transversal does not have to cross parallel lines.

• A line that crosses only one line is not a transversal.

• It is not proper to say "transversal line" since the word transversal already means line.

• In practice, a transversal usually cuts parallel lines.