Etymograph

English

fathom

Fathom comes from Middle English fathome ‘unit of length of about six feet’, from Old English fæþm ‘encircling or outstretched arms, bosom, embrace’, and ultimately from Proto-Indo-European *pet- ‘to spread out’.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*pet-1‘to spread out’reconstructed
  2. Proto-Germanicc. 500 BCE–200 CE*faþmaz1‘outstretched arms, embrace’reconstructed
  3. Proto-West Germanicc. 200–500 CE*faþm1‘outstretched arms, embrace’reconstructed
  4. Old Englishc. 450–1150fæþm1‘encircling or outstretched arms, bosom, embrace’
  5. Middle Englishc. 1150–1500fathome1‘unit of length of about six feet’
  6. Englishearliest quotation 1601fathom1

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, English fathom
  2. Earliest quotation in Wiktionary’s entry: 1601, Thomas Dekker: “Thy Bride, thy choice, thy vvife, / She that…”.

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*pet-Wiktionary, English fathom‘to spread out’reconstructed
  2. Proto-Germanicc. 500 BCE–200 CE*faþmazWiktionary, English fathom‘outstretched arms, embrace’reconstructed
  3. Proto-West Germanicc. 200–500 CE*faþmWiktionary, English fathom‘outstretched arms, embrace’reconstructed
  4. Old Englishc. 450–1150fæþmWiktionary, English fathom‘encircling or outstretched arms, bosom, embrace’
  5. Middle Englishc. 1150–1500fathomeWiktionary, English fathom‘unit of length of about six feet’
  6. Englishearliest quotation 1601fathomWiktionary, English fathom. Earliest quotation in Wiktionary’s entry: 1601, Thomas Dekker: “Thy Bride, thy choice, thy vvife, / She that…”

Linked words

through Proto-Indo-European *pet- ‘to spread out’

passion, compatibility, petal, 4 more

Today it means

noun A man's armspan, generally reckoned to be six feet (about 1.8 metres). Later used to measure the depth of water, but now generally replaced by the metre outside American usage.

Sources

Sources: Wiktionary, “fathom”. By Wiktionary contributors, CC BY-SA 4.0, via kaikki.org (dump of Oct 3 2026); text adapted and restructured. Language periods are conventional ranges, not dates for this word. License.

Etymograph / Proto-Indo-European *pet- / fathom

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