The American Cyclopædia (1879)/X
X, THE 24th letter of the English alphabet. It represents in English, and generally in French also, the combined sounds of cs as in the word texture, and of gs as in the word example, except at the beginning of words, where it has the sound of z. Its form and position in the alphabet are apparently borrowed from those of the Greek χ, while its sound is that of ξ, the 14th letter of the Greek alphabet. In Italian it is not used, s and c being substituted for it, as in esatto, exact, eccellente, excellent. In Spanish it has at the end of syllables the same value as in English; at their beginning it is, like the Spanish j, a guttural, nearly equivalent to the German ch. In Portuguese it represents several sounds, but most frequently that of the English sh. In Russian the X represents the sound, as it retains the character, of the Greek χ. As a Latin numeral, X stands for 10; the Greek ξ stood for 60, and χ for 600.