1. (v.t.)x to cross out or mark with an x (often fol. by out): to x out an error.
2. x to indicate choice, as on a ballot or examination (often fol. by in): to x in the candidate of your choice.
3. X experimental.
4. X extra.
5. X Slang.
6. X the 24th in order or in a series.
7. X (sometimes l.c.) the Roman numeral for 10.
8. X Christ.
9. X Christian.
10. X cross.
11. X reactance.
12. X a motion-picture rating applied to sexually graphic or explicit films.
13. X (formerly) such a rating advising that persons under the age of 17 would not be admitted to the film.
14. X a person, thing, agency, factor, etc., of unknown identity.
15. x experimental.
16. x extra.
17. x an unknown quantity or a variable.
18. x (used at the end of letters, telegrams, etc., to indicate a kiss.)
19. x (used to indicate multiplication) times: 8 &xtimes; 8 = 64.
20. x (used between figures indicating dimensions) by: 3″&xtimes; 4″ (read: “three inches by four inches”).
21. x power of magnification: a 50x telescope.
22. x (used as a signature by an illiterate person.)
23. x cross.
24. x (used to indicate a particular place or point on a map or diagram.)
25. x (used to indicate choice, as on a ballot or examination.)
26. x (used to indicate an error or incorrect answer, as on a test.)
27. x a person or thing of unknown identity.
Definition of 'x'
Princeton's WordNet
1. (noun)ten, 10, X, tenner, decade the cardinal number that is the sum of nine and one; the base of the decimal system
2. (noun)X, x, ex the 24th letter of the Roman alphabet
3. (adj)Adam, ecstasy, XTC, go, disco biscuit, cristal, X, hug drug street names for methylenedioxymethamphetamine
4. (adj)ten, 10, x being one more than nine
Definition of 'x'
Webster Dictionary
1. 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. See Guide to Pronunciation, // 217, 270, 271
Definitions of 'x'
The New Hacker's Dictionary
1. x 1. Used in various speech and writing contexts (also in lowercase)
in roughly its algebraic sense of ‘unknown within a set defined by
context’ (compare N). Thus, the abbreviation
680x0 stands for 68000, 68010, 68020, 68030, or 68040, and 80x86 stands for
80186, 80286, 80386, 80486, 80586 or 80686 (note that a Unix hacker might
write these as 680[0-6]0 and 80[1-6]86 or 680?0 and 80?86 respectively; see
glob).
2. [after the name of an earlier window system called
‘W’] An over-sized, over-featured, over-engineered and
incredibly over-complicated window system developed at MIT and widely used
on Unix systems.
Definitions of x 
