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[uhn-fath -uh-muh-buh l] /ʌnˈfæð ə mə bəl/
not able to be fathomed, or completely understood; incomprehensible:
heroism in the face of unfathomable conflict.
not able to be measured with a sounding line, or fathomed:
unfathomable depths of the ocean.
Related forms
unfathomableness, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for unfathomable
Contemporary Examples
Historical Examples
  • And with her straight, unfathomable glance she answered that she would be so, of course.

    The Secret Agent Joseph Conrad
  • His eyes were dark, and they held an unfathomable melancholy.

    Tiverton Tales Alice Brown
  • As she turned to go her eyes thanked him with an unfathomable glance.

    The Black Bag Louis Joseph Vance
  • Is it pale and gray with heat, full of sunshine, and unfathomable in depth?

  • They had leant, so to say, one on the other above an unfathomable depth, attracted to it by its horror.

    Therese Raquin Emile Zola
British Dictionary definitions for unfathomable


incapable of being fathomed; immeasurable
Derived Forms
unfathomableness, noun
unfathomably, adverb
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
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Word Origin and History for unfathomable

1610s, originally in the figurative sense, of feelings, conditions, etc., from un- (1) "not" + fathomable. Literal sense attested from 1670s. Related: Unfathomably.

Online Etymology Dictionary, © 2010 Douglas Harper
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