Definition of X:

• X, the twenty- fourth letter of the English alphabet, has three sounds; a compound nonvocal sound ( that of ks), as in wax; a compound vocal sound ( that of gz), as in example; and, at the beginning of a word, a simple vocal sound ( that of z), as in xanthic.
• 1. The Roman numeral 10. 2. In homeopathy, noting the decimal scale of dilutions or potencies; see potency. 3. Abbreviation for Kienboeck's unit. 4. Chemical symbol for xenon.
• Twenty- fourth letter of the alphabet. As a Roman numeral, it stands for ten; after a proper name, for the tenth, as Leo X.
• Is the twenty- fourth letter of the English alphabet. In the middle and at the end of words it has the sound of ks or qs. At the beginning of a word it has precisoly the sound of z. It is used as an initial only in a few words borrowed from the Greek. As a numeral, X stands for ten; when horizontal, for 1, 000; a dash over it, for ten thousand. It is the symbol of the unknown quantity in algebra. As an abbreviation, X. stands for Christ, as in Xn., Christian.
• the cardinal number that is the sum of nine and one; the base of the decimal system
• The twenty- fourth letter in the English alphabet.

Usage examples for X

1. " It used to be Smith," said T. X., " but no matter.  The Clue of the Twisted Candle by Edgar Wallace

2. Besides I can't get one o' them X- ray machines- they cost a heap.  The Panchronicon by Harold Steele Mackaye

3. The human eye is so constructed that it seems to have more than an X- ray power, for it can look through this atmosphere as readily as we can peer through ours.  Life in a Thousand Worlds by William Shuler Harris

4. I know Mr. X., and I do so want to speak to somebody.  An American Girl Abroad by Adeline Trafton