(chiefly nautical, historical) Originally, the distance between an adult man's arms stretched out away from the sides of his torso so that they make a straight line perpendicular to his body, measured from the tips of the longest fingers of each hand, generally reckoned to be six feet (about 1.8 metres); subsequently used as a unit for water depth but now generally replaced by the metre.

(also figuratively) To measure the depth of (water); to take a sounding of; to sound.

able to be fathomed

simple past tense and past participle of fathom

present participle of fathom

Third-person singular simple present indicative form of fathom

plural of fathom

The quality of being fathomable.

The quality of being fathomable.

One who fathoms.