Meaning & use
fathom
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Meanings
verbtransitive
To work out the meaning of something puzzling or hard to understand, after a lot of thought.
Grammar: Takes an object, and is most often used in negatives or questions: I cannot fathom his reasons.
Patterns
- fathom something
- fathom why/how something
I cannot fathom why anyone would leave such a good job.
Scientists are still trying to fathom how the signal was produced.
It is hard to fathom the scale of the disaster.
nouncountabletechnical
A unit for measuring water depth, equal to six feet or about 1.8 meters.
Grammar: After a number, the plural is often the same: ten fathom, though fathoms is also used.
Patterns
- X fathoms deep
The anchor rope was twenty fathoms long.
The wreck lies in thirty fathoms of cold water.
Old sea charts marked the depth in fathoms.
verbtransitivetechnicalold-fashioned
To measure how deep water is by lowering a weighted line.
Grammar: Takes an object such as a channel or harbor; mostly historical or nautical.
Patterns
- fathom the depth of something
The sailors fathomed the channel before steering in.
They fathomed the lake by lowering a lead weight on a rope.
Surveyors fathomed the harbor entrance each morning.
Word forms
| third person singular | fathoms |
|---|---|
| past tense | fathomed |
| past participle | fathomed |
| -ing form | fathoming |
| plural (noun) | fathoms or fathom |
Common combinations
- cannot fathom
- I cannot fathom how she finished so quickly.
- hard to fathom
- His sudden change of heart is hard to fathom.
- fathom the depths
- No one has fully fathomed the depths of the ocean trench.
- fathom out
- It took them an hour to fathom out the instructions.
- five fathoms deep
- The sunken ship lies five fathoms deep.
Synonyms and how they differ
- understand
- Understand is the plain, general word, while fathom suggests grasping something deep or puzzling after effort.
- comprehend
- Comprehend is more formal and can be used positively, whereas fathom mostly appears in negative statements.
- figure out
- Figure out is informal and implies solving a practical problem, while fathom suggests getting to the bottom of something mysterious.
- grasp
- Grasp stresses taking in an idea quickly, and fathom stresses reaching real depth of understanding.
Opposites
Word family
- fathomable adjective
- able to be understood or measured
- unfathomable adjective
- impossible to understand or measure
- fathomless adjective
- too deep to measure or understand
- fathomlessly adverb
- in a way too deep to measure
Commonly confused: fathom or phantom?
fathom vs phantom
A phantom is a ghost or illusion; it is pronounced differently and has nothing to do with understanding or depth.
Practice
I just cannot ____ why she would turn down such a generous offer.
Choose one answer.
Fathom means to understand something puzzling, and is common after cannot. Forbid and the others do not take a why-clause in this meaning.
Make it your own
Write a sentence using “fathom”, then check it and compare it with the examples above.