plural fathoms
: a unit of length equal to six feet (about 1.8 meters) used especially for measuring the depth of water
The water here is five fathoms deep.
fathoms; fathomed; fathoming
: to understand the reason for (something)
I couldn't fathom why she made such a foolish decision. = I couldn't fathom her reasons for making such a foolish decision.
(Brit) I couldn't fathom out her reasons.
Cite this Entry
“Fathom.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/fathom. Accessed 23 Apr. 2026.
Copy Citation
