What is meant by "depth" in measurements?

Depth refers to the measurement that indicates how deep something goes from a surface downward. This concept is commonly used in various fields such as geology, oceanography, and construction, where understanding how far below a reference point (like the ground or water surface) something extends is crucial.

In practical applications, depth can be important for determining water levels, digging basements, or measuring the thickness of materials. The correct choice emphasizes the directional aspect of depth, which is specifically concerned with the vertical distance from a reference surface downwards.