Kappa Is the Greek Letter Behind C and K
Kappa is the tenth letter of the Greek alphabet. It gave the Roman alphabet both its K and, indirectly, its C.
Kappa is the tenth letter of the Greek alphabet, written ฮ and ฮบ. It is one source of two Roman letters: the Etruscans borrowed both *kappa* and *gamma* for k-sounds, and Latin ended up with C doing most of the work while K survived in a handful of words. That is why English has two letters for one sound and inherits spellings like *cat* and *kitten* side by side. In statistics, *Cohen's kappa* measures agreement between raters.
- The Greek letter. *The letter kappa.*
- Cohen's kappa โ an agreement statistic. *A kappa of 0.8.*
- Kappa โ a Japanese water spirit. *A kappa in folklore.*
- Gamma โ the neighbouring letter. *Gamma rays.*
- Greek alphabet โ its home. *The Greek alphabet.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | kappa | The letter kappa. |
| Capital | ฮ | Capital kappa. |
| Lower case | ฮบ | Lower-case kappa. |
| Position | tenth | Tenth letter. |
| Related | K | The Roman K. |
- Kappa is the tenth Greek letter.Alphabet.
- Cohen's kappa measures rater agreement.Statistics.
- It lies behind both C and K.Alphabet history.
Greek letters in English use
- Alpha and beta โ first and second, hence alphabet
- Delta โ a triangular river mouth, from the letter's shape
- Iota โ the smallest letter, hence not one iota
- Kappa โ a statistic of agreement
- Omega โ the last letter, hence the end of something
Greek *kappa*, from a Semitic letter name, ultimately from a word for the palm of the hand.
Why does English have both C and K?
Both descend from Greek letters borrowed through Etruscan into Latin. C took most of the work, leaving K in a limited set of words.
What is Cohen's kappa?
A statistic measuring how much two raters agree beyond what chance alone would produce.