What is Depth ?
Depth is (noun) 1. a measurement of how deep something is The depth of the lake is 20m. The submarine dived to a depth of 200m. 2. the deepest or most extreme point In the depth of the Russian winter, temperatures can reach -45 degreesC. They have a house in the depths of rural Wales. the depths of despair complete lack of hope When he was in the depths of despair he thought of committing suicide. in depth thoroughly to study a subject in depth to carry out an in-depth study of a problem
source: Easier English, Student Dictionary Upper Intermediate Level