K is the eleventh letter of the modern English alphabet and the ISO basic Latin alphabet. Its name in English is kay (pronounced /ˈk/), plural kays.[1] The letter K usually represents the voiceless velar plosive.

K k
(See below)
Writing systemLatin script
TypeAlphabetic and Logographic
Language of originLatin language
Phonetic usage[k]
Unicode valueU+004B, U+006B
Alphabetical position11
Time period~-700 to present
Descendants  K


Կ կ
Հ հ
Խ խ
Variations(See below)
Other letters commonly used withk(x)


hieroglyph D

The letter K comes from the Greek letter Κ (kappa), which was taken from the Semitic kaph, the symbol for an open hand.[2] This, in turn, was likely adapted by Semitic tribes who had lived in Egypt from the hieroglyph for "hand" representing D in the Egyptian word for hand, d-r-t. The Semites evidently assigned it the sound value /k/ instead, because their word for hand started with that sound.[3]

In the earliest Latin inscriptions, the letters C, K and Q were all used to represent the sounds /k/ and /ɡ/ (which were not differentiated in writing). Of these, Q was used before a rounded vowel (e.g. EQO 'ego'), K before /a/ (e.g. KALENDIS 'calendis'), and C elsewhere. Later, the use of C and its variant G replaced most usages of K and Q. K survived only in a few fossilized forms such as Kalendae, "the calends".[4]

After Greek words were taken into Latin, the Kappa was transliterated as a C. Loanwords from other alphabets with the sound /k/ were also transliterated with C. Hence, the Romance languages generally use C, in imitating Classical Latin's practice, and have K only in later loanwords from other language groups. The Celtic languages also tended to use C instead of K, and this influence carried over into Old English.

Use in writing systems


Today, English is the only Germanic language to productively use "hard" c (outside the digraph ck) rather than k (although Dutch uses it in loaned words of Latin origin, and the pronunciation of these words follows the same hard/soft distinction as in English). The letter k is silent at the start of an English word when it comes before the letter n, as in the words "knight," "knife," "knot," "know," and "knee". Like J, X, Q, and Z, K is not used very frequently in English. It is the fifth least frequently used letter in the English language, with a frequency of about 0.8% in words.


The SI prefix for a thousand is kilo-, officially abbreviated as k—for instance, prefixed to "metre" or its abbreviation m, kilometre or km signifies a thousand metres. As such, people occasionally represent numbers in a non-standard notation by replacing the last three zeros of the general numeral with "K": for instance, 30K for 30,000.

Other languages

In most languages where it is employed, this letter represents the sound /k/ (with or without aspiration) or some similar sound.

Other systems

The International Phonetic Alphabet uses k for the voiceless velar plosive.

Ancestors, descendants and siblings

  • 𐤊 : Semitic letter Kaph, from which the following symbols originally derive
  • Κ κ/ϰ : Greek letter Kappa, from which K derives
  • К к : Cyrillic letter Ka, also derived from Kappa
  • K with diacritics: Ƙ ƙ Ꝁ ꝁ Ǩ ǩ Ḳ ḳ Ķ ķ Ⱪ ⱪ Ḵ ḵ
  • The Uralic Phonetic Alphabet uses various forms of the letter K:[6]
  •  : Subscript small k was used in the Uralic Phonetic Alphabet prior to its formal standardization in 1902[7]
  • Ʞ ʞ : Turned capital and small k were used in transcriptions of the Dakota language in publications of the American Board of Ethnology in the late 19th century.[8] Turned small k was also used for a velar click in the International Phonetic Alphabet but its use was withdrawn in 1970.

Ligatures and abbreviations

Computing codes

UTF-8754B1076B226 132 170E2 84 AA
Numeric character referenceKKkkKK
EBCDIC family210D214692
ASCII 1754B1076B
1 Also for encodings based on ASCII, including the DOS, Windows, ISO-8859 and nMacintosh families of encodings.

Other representation

Other usage

  • "K" replacing "C" in satiric misspelling.
  • K is the unit symbol for the kelvin, used to measure thermodynamic temperature.
  • K is the chemical symbol for the element potassium (K is an abbreviation of kalium, the Latin name for potassium).
  • Triangle K.
  • Unit prefix k, meaning 1000 times.
  • Josef K is the name of the principal character in Franz Kafka's novel The Trial.
  • In chess notation, the letter K represents the King (WK for White King, BK for Black King).
  • In baseball scoring, the letter K is used to represent a strikeout. A forwards oriented K represents a "strikeout swinging"; a backwards oriented K () represents a "strikeout looking".
  • As abbreviation for OK, often used in emails and short text messages.
  • K is used as a slang term for Ketamine among recreational drug users.
  • In the CMYK color model, K represents black ink.
  • In International Morse code it is used to mean "over".[10]
  • In fracture mechanics, K is used to represent the stress intensity factor.
  • In physics, k usually stands for Boltzmann's constant
  • K (logic).
  • K is used colloquially to mean kilometre (as in "a 10K run").
  • When expressing amounts of money, $20K means twenty thousand dollars.
  • In the United Kingdom under the old system (before 2001), a licence plate that begins with "K" for example "K123 XYZ" would correspond to a vehicle registered between August 1, 1992 and July 31, 1993. Again under the old system, a licence plate that ends with "K" for example "ABC 123K" would correspond to a vehicle that was registered between August 1, 1971 and July 31, 1972.


  1. "K" Oxford English Dictionary, 2nd edition (1989); Merriam-Webster's Third New International Dictionary of the English Language, Unabridged (1993); "kay," op. cit.
  2. "K". The Oxford English Dictionary, 2nd ed., 1977, online(registration required)
  3. Gordon, Cyrus H. (1970). "The Accidental Invention of the Phonemic Alphabet". Journal of Near Eastern Studies. 29 (3): 193. doi:10.1086/372069. JSTOR 543451.
  4. Sihler, Andrew L. (1995). New Comparative Grammar of Greek and Latin (illustrated ed.). New York: Oxford University Press. p. 21. ISBN 0-19-508345-8. Archived from the original on 2016-11-09. Retrieved 2016-10-18.
  5. "Latin Extended-D" (PDF). Archived (PDF) from the original on 2019-03-25. Retrieved 2019-03-06.
  6. Everson, Michael; et al. (2002-03-20). "L2/02-141: Uralic Phonetic Alphabet characters for the UCS" (PDF). Archived (PDF) from the original on 2018-02-19. Retrieved 2018-03-24.
  7. Ruppel, Klaas; Aalto, Tero; Everson, Michael (2009-01-27). "L2/09-028: Proposal to encode additional characters for the Uralic Phonetic Alphabet" (PDF). Archived (PDF) from the original on 2017-10-11. Retrieved 2018-03-24.
  8. Everson, Michael; Jacquerye, Denis; Lilley, Chris (2012-07-26). "L2/12-270: Proposal for the addition of ten Latin characters to the UCS" (PDF). Archived (PDF) from the original on 2019-03-30. Retrieved 2018-03-24.
  9. Everson, Michael; Baker, Peter; Emiliano, António; Grammel, Florian; Haugen, Odd Einar; Luft, Diana; Pedro, Susana; Schumacher, Gerd; Stötzner, Andreas (2006-01-30). "L2/06-027: Proposal to add Medievalist characters to the UCS" (PDF). Archived (PDF) from the original on 2018-09-19. Retrieved 2018-03-24.
  10. Stephen Phillips (2009-06-04). "International Morse Code". Archived from the original on 2014-02-12. Retrieved 2014-02-10.
  • Media related to K at Wikimedia Commons
  • The dictionary definition of K at Wiktionary
  • The dictionary definition of k at Wiktionary
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