in depth, extensively or thoroughly: Make a survey in depth of the conditions.
    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. 2019

British Dictionary definitions for out of one's depth



the extent, measurement, or distance downwards, backwards, or inwards
the quality of being deep; deepness
intensity or profundity of emotion or feeling
profundity of moral character; penetration; sagacity; integrity
complexity or abstruseness, as of thought or objects of thought
intensity, as of silence, colour, etc
lowness of pitch
nautical the distance from the top of a ship's keel to the top of a particular deck
(often plural) a deep, far, inner, or remote part, such as an inaccessible region of a country
(often plural) the deepest, most intense, or most severe partthe depths of winter
(usually plural) a low moral state; demoralizationhow could you sink to such depths?
(often plural) a vast space or abyss
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
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

Medicine definitions for out of one's depth




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.