The letter K comes from the Greek letter Κ, which was taken from the Semitickaph, the symbol for an open hand. This, in turn, was likely adapted by Semitic tribes who had lived in Egypt from the hieroglyph for "hand" representing /ḏ/ in the Egyptian word for hand, ⟨⟩. The Semites evidently assigned it the sound value instead, because their word for hand started with that sound. In the earliest Latin inscriptions, the letters C, K and Q were all used to represent the sounds and . Of these, Q was used before a rounded vowel, K before /a/, 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". After Greek words were taken into Latin, the Kappa was transliterated as a C. Loanwords from other alphabets with the sound 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.
Pronunciation and use
English
Today, English is the only Germanic language to productively use "hard" rather than . The letter is silent at the start of an English word when it comes before the letter, as in the words "knight," "knife," "knot," "know," and "knee". Like J, X, Q, and Z, the letter K is not used very frequently in English. It is the fifth least frequently used letter in the English language, with a frequency in words of about 0.8%.
Number
In the International System of Units, the SI prefix for one thousand is kilo-, officially abbreviated as k: for example, prefixed to metre/meter 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, as in 30K for 30,000.
Other languages
In most languages where it is employed, this letter represents the sound or some similar sound.
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.
When expressing amounts of money, $20K means twenty thousand dollars.
In the United Kingdom under the old system, 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.
