Usually associated with vibration wave modes. Transverse Wave is 90° to the Longitudinal Wave.
"In 1816 André-Marie Ampère gave Augustin-Jean Fresnel an idea that the polarization of light can be explained by the wave theory if light were a transverse wave.
By the year 1821, Fresnel was able to show via mathematical methods that polarization could be explained by the wave theory of light and only if light was entirely transverse, with no longitudinal vibration whatsoever." https://en.wikipedia.org/wiki/Light#Wave_theory
See Also
Figure 8.4 - Transverse Wave
Longitudinal
Rayleigh Wave
Transverse Wave