n.
   - the distance from the top or surface to the bottom of something or to a specified point within it. ▸the distance from the front to the back of something. ▸the apparent existence of three dimensions in a two-dimensional representation. 
- the quality of being intense or extreme. ▸complexity and profundity of thought. ▸comprehensiveness of study or detail: ![]()  third-year courses go into more depth. 
- 
(the depths)
 the deepest or lowest part of something.
Phrase
  
    - hidden depths
 previously unnoticed qualities.
- in depth
 in great detail; comprehensively and thoroughly.
- out of one's depth
 - in water too deep to stand in.
- in a situation beyond one's capabilities.
 
 
  Etymology
  ME: from deep + -th2, on the pattern of pairs such as long, length.