fathom
Americannoun
plural
fathoms,plural
fathomverb (used with object)
-
to measure the depth of by means of a sounding line; sound.
-
to penetrate to the truth of; comprehend; understand.
to fathom someone's motives.
noun
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a unit of length equal to six feet (1.829 metres), used to measure depths of water
-
mining a unit of volume usually equal to six cubic feet, used in measuring ore bodies
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forestry a unit of volume equal to six cubic feet, used for measuring timber
verb
-
to measure the depth of, esp with a sounding line; sound
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to penetrate (a mystery, problem, etc); discover the meaning of
Other Word Forms
- fathomable adjective
- fathomer noun
- unfathomable adjective
- unfathomed adjective
Etymology
Origin of fathom
First recorded before 900; Middle English fathme, Old English fæthm “span of outstretched arms”; cognate with German Faden “six-foot measure,” Old Norse fathmr; akin to Latin patēre “to stand open” ( patent )
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
"Can't even begin to fathom or process this," wrote Watt.
From Barron's • Feb. 22, 2026
She couldn’t fathom why Utah hadn’t put up more of a fight to keep Sundance in town as it seemed to her that it had been a fiscal boon.
From Los Angeles Times • Jan. 25, 2026
It is "hard to fathom just how quickly Heated Rivalry took the world by storm", Radio Times said last month.
From BBC • Jan. 7, 2026
"You just wouldn't even fathom that something like this would happen," 31-year-old Mary, who is originally from the UK, tells the BBC.
From BBC • Dec. 21, 2025
I couldn’t fathom why anyone would want to do such a thing or how anyone could think they were doing it.
From "Insignificant Events in the Life of a Cactus" by Dusti Bowling
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
