fathom
Americannoun
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fathoms,
plural
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fathom
plural
verb (used with object)
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fathoms,
present (3rd person singular)
-
fathomed,
past participle, past
-
fathoming
present participle
-
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
-
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
-
forestry a unit of volume equal to six cubic feet, used for measuring timber
verb
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to measure the depth of, esp with a sounding line; sound
-
to penetrate (a mystery, problem, etc); discover the meaning of
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Participles
Conjugated Forms
Present
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fathomsimple
-
fathomssimple
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have fathomedperfect
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has fathomedperfect
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am fathomingprogressive
-
are fathomingprogressive
-
is fathomingprogressive
-
have been fathomingperfect progressive
-
has been fathomingperfect progressive
Past
-
fathomedsimple
-
had fathomedperfect
-
was fathomingprogressive
-
were fathomingprogressive
-
had been fathomingperfect progressive
Future
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” ( see patent)
Explanation
To fathom something is to understand it thoroughly. It's usually used in the negative, as in "I can't fathom why he doesn't want to go along with us." Fathom is from Middle English fadme, from Old English fæthm, "outstretched arms." The Old English and modern English noun also refers to a unit of length used to measure the depth of water. The sense of intellectual depth comes from that meaning — to understand or fathom something thoroughly is "to get to the bottom of it."
Vocabulary lists containing fathom
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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.
See Examples For:
When we imagine, for example, those questions we can no longer ask a loved one who has died, such queries, Ms. Watson suggests, help “our brains to process loss, our minds to fathom the unfathomable.”
From The Wall Street Journal ● Aug. 4, 2026
The only solution Owens and Austin Baurichter could fathom then was creating a ballot measure.
From Salon ● Jul. 9, 2026
He complained to some that Washington never spoke, was hard to fathom, that his mind seemed busy.
From The Wall Street Journal ● Jun. 26, 2026
“It’s hard to fathom that you’re watching the exploding d— and driving through whales, and you’re like, ‘Wow, this really feels threatening to us in any political way,’” Kripke says.
From Los Angeles Times ● Jun. 10, 2026
He couldn't fathom what was stirring in the prince's mind.
From "The Whipping Boy" by Sid Fleischman
DaCosta fathoms the deepest notes in Ibsen’s classic as though they were whale song, remixing them into her own ode to a woman who needs healthier hobbies.
From Los Angeles Times ● Mar. 10, 2026
In the late 1800s the Yup’ik people from the Alaskan coast recorded building kayaks that were 2.5 fathoms long plus a cockpit, which was the length of an arm with a closed fist.
From Science Magazine ● May 31, 2023
“He’s playing it off. I don’t think he fathoms how bad this is. Shame on him. I hope he gets what he deserves.”
From Washington Times ● Jul. 6, 2021
And after some initial tests in the shallow water, the Thresher headed out to where the ocean was 1,400 fathoms, or a mile and half, deep.
From Washington Post ● Sep. 26, 2019
Rounding the corner they saw before them a low cliff, some five fathoms high, with a broken and jagged top.
From "The Fellowship of the Ring" by J.R.R. Tolkien
Ken Ono’s career as one of the world’s most prominent mathematicians has taken him to Hollywood and the Olympics, places that he never could have fathomed.
From The Wall Street Journal ● Dec. 7, 2025
"We never fathomed it would be this catastrophic and apocalyptic."
From BBC ● Jan. 14, 2025
Gmail’s existence is also why other free email services and the internal email accounts that employees use on their jobs offer far more storage than was fathomed 20 years ago.
From Seattle Times ● Mar. 31, 2024
Brandishing a competitive nature and an extreme love of live entertainment, TV and movies since childhood, she never could have fathomed that a blend of all of those attributes could equate to a job.
From Los Angeles Times ● Mar. 7, 2024
The thing she’d wanted, the thing she dreamed of, belonged to her and was better than anything she could have fathomed.
From "Night Owls" by A.R. Vishny
Climate change is what philosopher Timothy Morton calls a hyperobject: something that so massively occupies space and time that our puny primate brains have trouble fathoming them.
From Salon ● Dec. 31, 2025
Medvedev had difficulty fathoming that he’d have to win the Australian Open every year until he was 34 to match Djokovic’s success there.
From Los Angeles Times ● Feb. 21, 2021
They are like the proverbial worker who knows how to use a hammer and thus sees everything as a nail—not fathoming the existence of other tools.
From Scientific American ● Jun. 8, 2020
Until recently, Corker, an admirable man and talented legislator, has been, like many other people, prevented by his normality from fathoming Trump’s abnormality.
From Washington Post ● Oct. 13, 2017
We work for the pleasure of working, of fathoming the secrets of nature, and of instructing ourselves.
From Mysterious Psychic Forces An Account of the Author's Investigations in Psychical Research, Together with Those of Other European Savants by Camille Flammarion
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.
