1. [n]  degree of psychological or intellectual depth
2. [n]  extent downward or backward or inward; "the depth of the water"; "depth of a shelf"; "depth of a closet"
3. [n]  the intellectual ability to penetrate deeply into ideas
4. [n]  (usually plural) the deepest and most remote part; "from the depths of darkest Africa"; "signals received from the depths of space"
5. [n]  (usually plural) a low moral state; "he had sunk to the depths of addiction"

DEPTH is a 5 letter word that starts with D.

1. \Depth\ (s[e^]pth), n. [From {Deep}; akin to D. diepte,
   Icel. d[=y]pt, d[=y]p[eth], Goth. diupi[thorn]a.]
   1. The quality of being deep; deepness; perpendicular
      measurement downward from the surface, or horizontal
      measurement backward from the front; as, the depth of a
      river; the depth of a body of troops.
   
   2. Profoundness; extent or degree of intensity; abundance;
      completeness; as, depth of knowledge, or color.
   
            Mindful of that heavenly love Which knows no end in
            depth or height.                      --Keble.
   
   3. Lowness; as, depth of sound.
   
   4. That which is deep; a deep, or the deepest, part or place;
      the deep; the middle part; as, the depth of night, or of
      winter.
   
            From you unclouded depth above.       --Keble.
   
            The depth closed me round about.      --Jonah ii. 5.
   
   5. (Logic) The number of simple elements which an abstract
      conception or notion includes; the comprehension or
      content.
   
   6. (Horology) A pair of toothed wheels which work together.
      [R.]
   
   
   
   {Depth of a sail} (Naut.), the extent of a square sail from
      the head rope to the foot rope; the length of the after
      leach of a staysail or boom sail; -- commonly called the
      {drop of a sail}.
   
   

2. \Depth\, n. (A["e]ronautics)
   The perpendicular distance from the chord to the farthest
   point of an arched surface.
   
   

1. Vertical distance from the water surface to the streambed.
2. Vertical distance from crest or crown to invert of a conduit.