AskDefine | Define fathom

Dictionary Definition



1 a linear unit of measurement (equal to 6 feet) for water depth [syn: fthm]
2 (mining) a unit of volume (equal to 6 cubic feet) used in measuring bodies of ore [syn: fthm]


1 come to understand [syn: penetrate, bottom]
2 measure the depth of (a body of water) with a sounding line [syn: sound]

User Contributed Dictionary



Old English fæþm ‘outstretched arms’, from Germanic *faþmaz, from Indo-European *pet-. Cognate with Dutch vadem, vaam, German Faden, Swedish famn.


  • /ˈfæðəm/


  1. Grasp, envelopment, control.
  2. A measure of length corresponding to the outstretched arms, standardised to six feet, now used mainly for measuring depths in seas or oceans.


measure of length


  1. transitive archaic To encircle with outstretched arms, especially to take a measurement; to embrace.
  2. To measure the depth of, take a sounding of.
  3. transitive figuratively To get to the bottom of; to manage to comprehend (a problem etc.).
    I can't for the life of me fathom what this means.


(transitive, archaic) to encircle with outstretched arms
  • German: umarmen
(transitive) to measure the depth of, take a sounding of
  • German: loten, ausloten, sondieren
(transitive, figuratively) to manage to comprehend
  • French: saisir, comprendre
  • German: begreifen, verstehen, ergründen
  • Italian: capire, comprendere

Extensive Definition

A fathom is a unit of length in the Imperial system (and the derived U.S. customary units). The name derives from the Old English word fæðm meaning 'a pair of outstretched arms'. In Middle English it was fathme. Its size varied slightly depending on its base definition, either based on a thousandth of an (Admiralty) nautical mile or as a multiple of the imperial yard. There are 2 yards (6 feet) in a fathom.

International Fathom

One fathom is equal to:
  • 1.8288 metres (1 metre is about 0.5468 fathoms)
  • 2 yards (1 yard is exactly 0.5 fathoms)
  • 4 cubits (1 cubit is exactly 0.25 fathoms)
  • 6 feet (1 foot is about 0.1667 fathoms)
  • 18 hands
  • 72 inches
In 1954 the United States and countries of the Commonwealth of Nations defined the length of the international yard to be exactly 0.9144 metres. With the adoption of the metric SI system the use of fathoms declined.

British Fathom

The British Admiralty defined a fathom to be a thousandth of an imperial nautical mile (which was 6080 ft) or 6.08 feet. In practice the fathom was always regarded as exactly 6 feet. No conflict in the real world existed as depths on Imperial nautical charts were indicated in feet if less than 30 feet and in fathoms for depths above that.

Use of the fathom

The fathom is now of mainly historical interest. In most countries, it is an obsolete unit and has not been used in maritime affairs for decades. All nautical charts produced by Hydrographic Offices worldwide (except for those produced by the U.S. Hydrographic Office, which uses feet and fathoms. ) indicate depths in metres. Until early in the twentieth century, it was the unit used to measure the depth of mines (mineral extraction) in the United Kingdom.


It is customary, when burying the dead, to inter the corpse at a fathom's depth, or six feet under. A burial at sea (where the body is weighted to force it to the bottom) requires a minimum of six fathoms of water. This is the origin of the phrase to deep six, meaning to discard, or dispose of.

Other fathoms and similar units of length

Units of length similar to the size of the fathom can be found in many cultures. Some are listed below.

See also



fathom in Danish: Favn
fathom in German: Klafter
fathom in Estonian: Süld
fathom in Spanish: Braza (unidad)
fathom in Esperanto: Klafto
fathom in French: Brasse (unité de mesure)
fathom in Italian: Braccio (unità di misura)
fathom in Hebrew: פאתום
fathom in Hungarian: Öl
fathom in Dutch: Vadem
fathom in Japanese: ファゾム
fathom in Norwegian: Favn
fathom in Polish: Sążeń
fathom in Russian: Морская сажень
fathom in Slovenian: Seženj
fathom in Finnish: Syli
fathom in Swedish: Famn
fathom in Ukrainian: Фатом
fathom in Chinese: 噚

Synonyms, Antonyms and Related Words

absorb, answer, appraise, appreciate, apprehend, ascertain, assay, assess, assimilate, be acquainted with, be apprised of, be aware of, be cognizant of, be conscious of, be conversant with, be informed, be with one, bottom, calculate, calibrate, caliper, cast the lead, catch, catch on, check a parameter, clear up, cognize, comprehend, compute, conceive, conceptualize, crack, debug, decipher, decode, delve into, determine, dial, dig, dig into, digest, discern, disentangle, divide, divine, do, dope, dope out, estimate, evaluate, explain, explore, figure out, find out, find the answer, find the solution, follow, gauge, get, get hold of, get right, get the drift, get the idea, get the picture, go into, graduate, grasp, guess, guess right, have, have information about, have it, have it taped, have knowledge of, hit it, indagate, interpret, investigate, ken, know, learn, look into, make a sounding, make out, master, measure, mensurate, mete, meter, open the lock, pace, peer into, penetrate, perceive, pierce, plumb, plumb the depths, plumb-line, poke into, possess, prehend, prize, probe, pry into, psych, psych out, puzzle out, quantify, quantize, rate, ravel, ravel out, read, realize, recognize, resolve, riddle, savvy, search into, search out, see, seize, seize the meaning, sense, sift, size, size up, sling the lead, solve, sort out, sound, span, step, survey, take, take a reading, take in, take soundings, triangulate, understand, undo, unlock, unravel, unriddle, unscramble, untangle, untwist, unweave, valuate, value, weigh, work, work out, wot, wot of
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