fathom Meaning, Definition & Usage

  1. noun a linear unit of measurement (equal to 6 feet) for water depth
    fthm.
  2. noun (mining) a unit of volume (equal to 6 cubic feet) used in measuring bodies of ore
    fthm.
  3. verb come to understand
    penetrate; bottom.
  4. verb measure the depth of (a body of water) with a sounding line
    sound.

WordNet

Fath"om noun
Etymology
OE. fadme, fa&edh;me, AS. fæ&edh;m fathom, the embracing arms; akin to OS. fa&edh;mos the outstretched arms, D. vadem, vaam, fathom, OHG. fadom, fadum, G. faden fathom, thread, Icel. fa&edh;mr fathom, Sw. famn, Dan. favn; cf. Gr. to spread out, outspread, flat, L. patere to lie open, extend. Cf. Patent, Petal.
Definitions
  1. A measure of length, containing six feet; the space to which a man can extend his arms; -- used chiefly in measuring cables, cordage, and the depth of navigable water by soundings.
  2. The measure or extant of one's capacity; depth, as of intellect; profundity; reach; penetration. R.
    Another of his fathom they have none To lead their business. Shak.
Fath"om transitive verb
Wordforms
imperfect & past participle Fathomed ; present participle & verbal noun Fathoming
Definitions
  1. To encompass with the arms extended or encircling; to measure by throwing the arms about; to span. Obs. Purchas.
  2. The measure by a sounding line; especially, to sound the depth of; to penetrate, measure, and comprehend; to get to the bottom of. Dryden.
    The page of life that was spread out before me seemed dull and commonplace, only because I had not fathomed its deeper import. Hawthotne.

Webster 1913