fathom

From Middle English fathome, fadome, from Old English fæþm, fæþme (“outstretched or encircling arms, embrace, grasp, protection, interior, bosom, lap, breast, womb, fathom, cubit, power, expanse, surface”), from Proto-Germanic *faþmaz (“embrace”), from Proto-Indo-European *pet- (“to spread out, extend”). Cognate with Low German fadem, faem (“a cubit, thread”), Dutch vadem, vaam (“fathom”), German Faden (“thread, filament, fathom”), Danish favn (“embrace, fathom”), Norwegian Bokmål favn (“embrace, fathom”), Swedish famn (“the arms, bosom, embrace”), Icelandic faðmur (“embrace”), Latin pateō, Ancient Greek πετάννυμι (petánnumi).

• IPA^(key): /ˈfæðəm/

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fathom (plural fathoms)

1. (obsolete) Grasp, envelopment, control.
2. (units of measure, now usually nautical) An English unit of length for water depth notionally based upon the width of grown man's outstretched arms but standardized as 6 feet (about 1.8 m).

   Synonyms: brace, stade (obsolete), orguia (Greek)

   • 1983, Richard Ellis, The Book of Sharks, Knopf, →ISBN, page 7:

     At fifty fathoms, the waters of the Southern Ocean are dark blue.

3. (units of measure) Various similar units in other systems.
4. (figuratively) Depth of insight, mental reach or scope.
   • Shakespeare, Othello, Act I, Scene i, ll. 151-2:

     Another of his fathom they have none
     To lead their business.

fathom (third-person singular simple present fathoms, present participle fathoming, simple past and past participle fathomed)

1. (transitive, archaic) To encircle with outstretched arms, especially to take a measurement; to embrace.
2. (transitive) To measure the depth of, take a sounding of.
3. (transitive, figuratively) To get to the bottom of; to manage to comprehend; understand (a problem etc.).

   Synonyms: fathom out, figure out, puzzle out, work out

   I can't for the life of me fathom what this means.

   • 2018 April 10, Daniel Taylor, “Liverpool go through after Mohamed Salah stops Manchester City fightback”, in The Guardian (London)‎:

     Otamendi’s selection ahead of Vincent Kompany was difficult to fathom and, apart from Fernandinho, City’s line-up was otherwise filled with attacking players.

• fathomable
• fathometer
• fathomless
• fathom out
• unfathomable

• deep six

• fathom in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913.
• fathom in The Century Dictionary, New York, N.Y.: The Century Co., 1911.
• fathom at OneLook Dictionary Search
• fathom on Wikipedia.Wikipedia