longitudinal

adj

1. (not-comparable)Running across a set direction of an object.

   “The motion about the longitudinal axis of an airplane is called roll.”

2. (not-comparable)Running across a set direction of an object.

   “The units have transverse seats, two and three astride the passageway with single or double longitudinal seats alongside the two entrance vestibules in each car.”

   “The third rotation is about the longitudinal axis of the thigh.”

   “Unlike the older trains, the new units have walk-through carriages and longitudinal rather than transverse seating.”

3. (not-comparable)Relating to the geographical longitude.

   “The longitudinal position of a ship refers to its angular distance east or west from the prime meridian.”

4. (not-comparable)Of a study, sampling data over time rather than merely once.

   “longitudinal studies”

   “Examining national longitudinal data, Mossakowski has found that people who were unemployed for long periods in their teens or early 20s are far more likely to develop a habit of heavy drinking (five or more drinks in one sitting) by the time they approach middle age.”

noun

1. Any longitudinal piece, as in shipbuilding etc.
2. A railway sleeper lying parallel with the rail.