chi

The word “chi” means the 22nd letter of the Greek alphabet, written Χ, χ. In plain terms, either the Greek letter X, or (in a completely separate, Chinese-derived sense) the life-force energy talked about in tai chi and traditional medicine.

“Chi” is pronounced keye (/kaɪ/ in IPA).

Here is “chi” used in a sentence: “The symbol chi looks like the letter X.”

Words with a similar meaning to “chi” include Taiwanese foot, Hong Kong foot and chek.

“Chi” is a noun.

The word “chi” comes from Ancient Greek. From Latin chī, taken from Ancient Greek χεῖ (kheî), the name of the letter Χ.

“Chi” is a fairly common word in modern English.

“Chi” has 2 distinct senses listed in this dictionary. The most common is: the 22nd letter of the Greek alphabet, written Χ, χ.

Chi and qi are two English spellings of the same Chinese concept of vital life-energy flowing through the body. 'Qi' follows the modern Pinyin romanization system, while 'chi' comes from the older Wade-Giles system, so both refer to exactly the same idea.

Not exactly. Although both are spelled 'chi' in English, the 'chi' in tai chi comes from a different Chinese word (part of 'taiji', roughly 'supreme ultimate') than the 'chi' meaning life-energy. Tai chi is often practised to cultivate that life-energy, but the two words are distinct in Chinese.

These are unrelated meanings that happen to share the English spelling. One is the 22nd letter of the Greek alphabet, written Χ or χ, while the other is the vital energy of Chinese philosophy and medicine, also spelled qi.

The Greek letter chi (χ) is best known in statistics from the chi-squared test, written χ², which measures how far observed results differ from expected ones. It also appears in various scientific formulas as a standard variable symbol.