- a unit of length equal to six feet (1.8 meters): used chiefly in nautical measurements. Abbreviation: fath
- 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.
- a unit of length equal to six feet (1.829 metres), used to measure depths of water
- a unit of volume usually equal to six cubic feet, used in measuring ore bodies
- a unit of volume equal to six cubic feet, used for measuring timber
- to measure the depth of, esp with a sounding line; sound
- to penetrate (a mystery, problem, etc); discover the meaning of