What is a trough? is it the highest part on a transfer wave, the lowest part on a transverse wave, the height of a transverse wave

This highest point is called the crest, and the lowest point is called the trough.

Explanation:

A trough is an elongated region of relatively low atmospheric pressure without a closed isobaric contour that would define it as a low pressure area. Since low pressure implies a low height on a pressure surface, troughs and ridges refer to features in an identical sense as those on a topographic map