1. a dimension taken through an object or body of material, usually downward from an upper surface, horizontally inward from an outer surface, or from top to bottom of something regarded as one of several layers.
  2. the quality of being deep; deepness.
  3. complexity or obscurity, as of a subject: a question of great depth.
  4. gravity; seriousness.
  5. emotional profundity: the depth of someone's feelings.
  6. intensity, as of silence, color, etc.
  7. lowness of tonal pitch: the depth of a voice.
  8. the amount of knowledge, intelligence, wisdom, insight, feeling, etc., present in a person's mind or evident either in some product of the mind, as a learned paper, argument, work of art, etc., or in the person's behavior.
  9. a high degree of such knowledge, insight, etc.
  10. Often depths. a deep part or place: from the depths of the ocean.
  11. an unfathomable space; abyss: the depth of time.
  12. Sometimes depths. the farthest, innermost, or extreme part or state: the depth of space; the depths of the forest; the depths of despair.
  13. Usually depths. a low intellectual or moral condition: How could he sink to such depths?
  14. the part of greatest intensity, as of night or winter.
  15. Sports. the strength of a team in terms of the number and quality of its substitute players: With no depth in the infield, an injury to any of the regulars would be costly.
  1. in depth, extensively or thoroughly: Make a survey in depth of the conditions.
  2. out of/beyond one's depth,
    1. in water deeper than one's height or too deep for one's safety.
    2. beyond one's knowledge or capability: The child is being taught subjects that are beyond his depth.

Origin of depth

1350–1400; Middle English depthe, equivalent to dep (Old English dēop deep) + -the -th1
Related formsdepth·less, adjective

Antonyms for depth Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for out of one's depth


  1. the extent, measurement, or distance downwards, backwards, or inwards
  2. the quality of being deep; deepness
  3. intensity or profundity of emotion or feeling
  4. profundity of moral character; penetration; sagacity; integrity
  5. complexity or abstruseness, as of thought or objects of thought
  6. intensity, as of silence, colour, etc
  7. lowness of pitch
  8. nautical the distance from the top of a ship's keel to the top of a particular deck
  9. (often plural) a deep, far, inner, or remote part, such as an inaccessible region of a country
  10. (often plural) the deepest, most intense, or most severe partthe depths of winter
  11. (usually plural) a low moral state; demoralizationhow could you sink to such depths?
  12. (often plural) a vast space or abyss
  13. beyond one's depth or out of one's depth
    1. in water deeper than one is tall
    2. beyond the range of one's competence or understanding
  14. in depth thoroughly or comprehensivelySee also in-depth

Word Origin for depth

C14: from dep deep + -th 1
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for out of one's depth



late 14c., apparently formed in Middle English on model of length, breadth; from Old English deop "deep" (see deep) + -th (2). Replaced older deopnes "deepness." Though the English word is relatively recent, the formation is in Proto-Germanic, *deupitho-, and corresponds to Old Saxon diupitha, Dutch diepte, Old Norse dypð, Gothic diupiþa.

Online Etymology Dictionary, © 2010 Douglas Harper

out of one's depth in Medicine


  1. The extent, measurement, or dimension downward, backward, or inward.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Idioms and Phrases with out of one's depth

out of one's depth

Also, beyond one's depth. Outside one's understanding or competence, as in He was out of his depth in that advanced calculus class, or The conductor realized that playing the fugue at the right tempo was beyond their depth. This expression alludes to being in water so deep that one might sink. [c. 1600] Also see over one's head.


see in depth; out of one's depth.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.