One of a set of parallel lines.

Direction conformable to that of another line.

A line of latitude.

“The 31st parallel passes through the center of my town.”

To construct or place something parallel to something else.

Of a path etc: To be parallel to something else.

Of a process etc: To be analogous to something else.

Equally distant from one another at all points.

“The horizontal lines on my notebook paper are parallel.”

Having the same overall direction; the comparison is indicated with "to".

“The two railway lines are parallel.”

(hyperbolic geometry, said of a pair of lines) Either not intersecting, or coinciding.

With a parallel relationship.

“The road runs parallel to the canal.”