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flat

Etymology and origin of the English word flat

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English has two words spelled flat: “level”, from Old Norse, and the apartment, an alteration of Scots flet, from Old English; the two are related.[1][2][3]

Pronunciation

  • IPA: /flæt/[4]

flat1 level

Confidence
Established
Formation
Borrowing
First attested
c. 1300
Borrowed from
Old Norse flatr via Middle English
Ultimate origin
Old Norse (flatr)

Etymology

The level is inherited from Middle English flat,[5] borrowed from Old Norse flatr (“flat”),[6][1][2][7] from Proto-Germanic *flataz,[2] which is also the source of Old Saxon flat “flat, shallow” and Old High German flaz “flat, level”,[6][1][5] from Proto-Indo-European *plat- (“to spread”),[6] the root also of Greek platýs “flat, broad” and Latvian plañdît “to make broad”.[1][5] Hoad calls the Germanic word of uncertain origin.[2] It is related to place and plate.[1][5]

Earliest recorded meaning

Stretched out, prostrate, lying at full length: about 1300 in Etymonline[6] and Barnhart,[1] and about 1320 in the OED.[8] The noun “level ground” is in place names from 1167, as Kirkeflat.[1][6]

Semantic evolution

“Level, all in one plane, even” is from the mid-14th century, and “without curvature” from about 1400.[6][8] Of a building levelled with the ground it is from 1560.[8] “Prosaic, dull”, from the notion of featureless, is from the 1570s,[6] and of drink from about 1600.[6] Of musical notes, lower than the intended pitch, it is from the 1590s,[6] first recorded in Shakespeare's Two Gentlemen of Verona (1594);[1] the flat sign and the natural sign are modified forms of the letter b.[6] The adverb “absolutely, downright” is from the 1550s.[6] A flat surface, as of a sword, is from the late 14th century, and a low shoe from 1834.[6] The flat tyre is from 1908,[6] flat-earth from 1876,[6] and flat out, first in motor racing, from 1932.[6] To flatline, to die, after the straight line on a heart monitor, dates from the 1970s.[3]

Timeline

  • 1167 – the place name Kirkeflat.[1]
  • c. 1300 – prostrate.[6][1]
  • mid-14th century – level, even.[6]
  • 1550s – adverb, absolutely.[6]
  • 1570s – dull.[6]
  • 1594 – of a musical note.[1]
  • c. 1600 – of drink.[6]
  • 1908 – flat tyre.[6]
  • 1932 – flat out.[6]

Modern meaning

Adjective

  1. Having a level surface without slope or curve.
  2. Smooth and even.
  3. Broad and thin.
  4. Lying at full length; prostrate.
  5. Dull and lifeless; of a drink, no longer fizzy.
  6. Fixed; unvarying: a flat rate.
  7. Of a tyre, deflated.
  8. In music, lower than the correct pitch, or a semitone lower than the natural note.

Adverb

  1. Level with the ground; at full length.
  2. Directly; completely: flat broke.
  3. Exactly: in ten seconds flat.

Noun

  1. A flat surface or part.
  2. A stretch of level ground, often by water.
  3. A deflated tyre.
  4. In music, a flat note, or the sign ♭.

Word family

  • flatly
  • flatness
  • flatten
  • flattish
  • flatfish
  • flatfoot
  • flatboat
  • flatcar
  • flatiron
  • flatline

flat2 apartment

Confidence
Established
Formation
Inherited
First attested
1801
Inherited from
Scots flet
Ultimate origin
Proto-Germanic (*flatjam)

Etymology

The apartment is inherited from Scots flet (“floor or storey of a house, inner part of a house”),[1][2] altered by association with flat “level”,[2] inherited from Middle English flet (“room, hall”),[1] inherited from Old English flett (“a dwelling, hall; floor, ground”),[6][1] from Proto-Germanic *flatjam,[6][2] a derivative of *flataz “flat”,[2] from Proto-Indo-European *plat- (“to spread”).[6] Old Saxon flet “room, house” and Old High German flezzi “floor” are cognates.[1]

Earliest recorded meaning

A floor or storey of a house: 1801, Scottish,[1][8][6] with the Old English word for a dwelling or floor going back to about 725, in Beowulf.[1]

Semantic evolution

A set of rooms on one floor, forming a residence, is first recorded in Scott's Redgauntlet (1824).[1][8][6] The word is chiefly British,[1][9] and Americans say apartment.[10]

Timeline

  • c. 725 – Old English flett, in Beowulf.[1]
  • 1801 – a storey.[1][8]
  • 1824 – an apartment.[1][8]

Modern meaning

Noun

  1. (chiefly British) A set of rooms on one floor forming a home; an apartment.

Word family

  • flatmate
  • flatlet

References

  1. ^ a b c d e f g h i j k l m n o p q r s t u v Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  2. ^ a b c d e f g h Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
  3. ^ a b Cresswell, Julia (2021), Oxford Dictionary of Word Origins, 3rd ed., Oxford: Oxford University Press
  4. ^ Jones, Daniel (2011), Cambridge English Pronouncing Dictionary, 18th ed., ed. Peter Roach, Jane Setter and John Esling, Cambridge: Cambridge University Press
  5. ^ a b c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  6. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z 27 Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  7. ^ Pearsall, Judy, ed. (1998), The New Oxford Dictionary of English, Oxford: Clarendon Press
  8. ^ a b c d e f g Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
  9. ^ Collins English Dictionary (2023), Glasgow: HarperCollins
  10. ^ The American Heritage Dictionary of the English Language (1992), 3rd ed., Boston: Houghton Mifflin

Related etymologies

Cite this entry

“Flat.” Etymologically, 15 Oct. 2026, etymologically.com/en/flat. Accessed 15 Oct. 2026.

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