K

The letter K (minuscule: k) is the eleventh letter of the Latin alphabet. It is used in the modern English alphabet and in many other western European languages.

In English, we call this letter "kay," and we say it like "kay" (pronounced /ˈkeɪ/ ).

The letter K most often makes a soft "k" sound at the back of the mouth. This sound is called the voiceless velar plosive. It is an important letter in words and names in many languages.

History

The letter K began with the Greek letter Κ (kappa). The Greeks got it from the west Semitic kaph, which meant an open hand.

K joined the Latin alphabet as ka to make it different from C (ce) and Q (qu). At first, Latin used C, K, and Q for the same sounds. Later, C and G were used more, and K was mostly left for old words like Kalendae.

Use in writing systems

English

The letter usually stands for the sound /k/ in English. It is quiet when it comes before ⟨n⟩ at the start of a word, like in knight, knife, knot, know, and knee. It is also quiet after a prefix, such as in unknowable, and in some compound words like penknife.

English is the only Germanic language that often uses "hard" ⟨c⟩ instead of ⟨k⟩, except when ⟨c⟩ is part of the pair ⟨ck⟩. The letter K is not used very often in English.

Other languages

In many languages, the letter K represents the sound /k/ or a similar sound.

Other systems

The International Phonetic Alphabet uses ⟨k⟩ to show the voiceless velar plosive.

Other uses

• In the International System of Units (SI), the SI prefix for one thousand is kilo-, officially written as k: for example, adding it to metre or meter gives kilometre or km, meaning a thousand metres. Sometimes people use K to replace the last three zeros in a number, like 30K for 30,000.
• The letter K stands for the unit kelvin, which is used to measure temperature.
• K is the chemical symbol for the element potassium.
• In chess notation, K represents the King (WK for White King, BK for Black King).
• In baseball scoring, K shows a strikeout. A normal K means a swinging strikeout, while an upside-down K means a strikeout looking.
• K is sometimes used to mean OK in emails and text messages.
• In the CMYK color model, K stands for black ink.
• In International Morse code, it means "over".
• In physics, k often represents the Boltzmann constant.
• In Argentinian politics, K is a symbol for Kirchnerism.
• K (logic).
• In the United Kingdom under the old system before 2001, a licence plate starting with "K" like "K123 XYZ" showed a vehicle registered between August 1, 1992, and July 31, 1993. A plate ending with "K" like "ABC 123K" showed a vehicle registered between August 1, 1971, and July 31, 1972.
• On Idaho license plates, a plate starting with K like "K123 ABC" means it was issued in Kootenai County.

Related characters

Ancestors, descendants and siblings

The letter K has many related symbols and forms. It comes from the ancient Semitic letter Kaph. This led to the Greek letter kappa. From Greek kappa we get the letter K we use today. We also get the Cyrillic letter Ka. There are special versions of K with marks added above or below, such as Ƙ ƙ, Ꝁ ꝁ, and Ḱ ḱ.

Some special forms of K were used in older writing systems. For example, turned versions of K were used to write the Dakota language in the past. There are also special symbols used in phonetic studies to show unique sounds.

Ligatures and abbreviations

Some symbols look like K but are used for different purposes. For example, the symbol ₭ stands for the Lao kip, a type of money. Other special K-like symbols were used in old handwriting to make writing faster.

Other representations

The letter K is used in many ways beyond just writing. In computers and other kinds of technology, it helps show different codes and symbols. It is an important part of how we share and understand information every day.