Depth  n. 1 a deepness. B measurement from the top down, from the surface inwards, or from front to back. 2 difficulty; abstruseness. 3 a wisdom. B intensity of emotion etc. 4 intensity of colour, darkness, etc. 5 (usu. In pl.) A deep water or place; abyss. B low, depressed state. C lowest, central, or inmost part (depths of the country; depth of winter).  in depth thoroughly. Out of one's depth 1 in water over one's head. 2 engaged in a task etc. Too difficult for one. [related to *deep]