X is the twenty-fourth letter of the Latin alphabet. It is in the form of St Andrew's Cross. In the NATO phonetic alphabet it is X-Ray.

A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z

/ks/ was in Ancient Greece written as Chi 'Χ' (Western Greek) or Xi 'Ξ' (Eastern Greek). In the end, Chi was standardized as /k_h/ (/x/ in Modern Greek) as well as Xi for /ks/. But the Etruscans took over X from older Western Greek, therefore, it stood for /ks/ in Etruscan and /ks/ and /gs/ [gz] in Latin. Only in Azeri, Uzbek and Tatar is X pronounced [kh]. Some scholars claim that Latin X is not identical with Greek X.

It is also controversial whether Psi, Chi (Khi) and Xi are Greek inventions or whether they are ultimately of Semitic origin.

X-ray represents the letter X in the NATO phonetic alphabet.

In context, X is also used as or in:

Two-letter combinations starting with X:
  • xa xb xc xd xe xf xg xh xi xj xk xl xm xn xo xp xq xr xs xt xu xv xw xx xy xz