Noah Webster
X
X, the twenty fourth letter of the English Alphabet, is borrowed from the Greek. In the middle and at the end of words, it has the sound of ks, as in wax, lax, luxury. At the beginning of a word, it has precisely the sound of z. It is used as an initial, in a few words borrowed from the Greek.
As a numeral, x stands for ten. It represents one V, which stands for five, placed on the top of another. When laid horizontally it stands for a thousand, and with a dash over it, it stands for ten thousand. As an abbreviation, x Stands for Christ, and in Xn. Christian; Xm. Christmas.