Consider up & down, left & right, and back & forth. Up & down can be stated generically as "vertical". Side-to-side is "lateral". What about back & forth?
What about the word longitudinal?
OOD defines longitudinal as "running lengthwise rather than across".
When we talk about waves in which the displacement of the medium is in the same direction as (or the opposite direction to) the direction in which the wave travels, we often use the word longitudinal.
In a Wikipedia article about aircraft principal axes, it states that
An aircraft in flight is free to rotate in three dimensions: pitch, nose up or down about an axis running from wing to wing, yaw, nose left or right about an axis running up and down; and roll, rotation about an axis running from nose to tail. The axes are alternatively designated as lateral, vertical, and longitudinal.