Webster's Revised Unabridged Dictionary · 1913

Longitudinal

Longitudinal , adjective

[Compare French longitudinal.]

1.
Of or pertaining to longitude or length; as, longitudinal distance.
2.
Extending in length; in the direction of the length; running lengthwise, as distinguished from transverse; as, the longitudinal diameter of a body. — Cheyne

Longitudinal , noun

A railway sleeper lying parallel with the rail.