Meaning of X in English


I. ˈeks noun

( plural x's or xs or x'es or xes ˈeksə̇z)

Usage: often capitalized, often attributive


a. : the 24th letter of the English alphabet

b. : an instance of this letter printed, written, or otherwise represented

c. : a speech counterpart of orthographic x (as x in xylophone, extra, next, or ox )

2. : ten — see number table

3. : a printer's type, a stamp, or some other instrument for reproducing the letter x

4. : someone or something arbitrarily or conveniently designated x: as

a. : the 24th in order or class

b. : the 23d in order or class when j is not used

c. : the 21st in order or class when j, v, and w are not used

d. : the first in an order or class including x, y, and sometimes z


a. : unknown quantity 1

find the value of x in the equation x -4 2 =3

b. : an arbitrarily chosen value from the domain of a variable

in the equation y=x 2 , let x =4

c. : x-coordinate


a. : something (as a cross) having the shape of the letter X

b. : something (as a $10 bill) marked with an X


[so called from the use of the letter in crossing out mistakes in writing]

: something (as a statement, answer, or result) that is wrong : mistake , error

8. x's plural , often capitalized : atmospherics 1

9. : the basic or monoploid number of chromosomes of a polyploid series : the number contained in a single genome — compare n

II. transitive verb

( x-ed also x'd or xed ; x-ed also x'd or xed ˈekst ; x-ing or x'ing ˈeksiŋ ; x'es or xes ˈeksə̇z)

1. : to mark with an x

x-ed his ballot clearly

2. : to cancel or obliterate with or as if with a series of x's — usually used with out

x-ing out most of what he had written

III. abbreviation

Usage: often capitalized

1. cross

2. ex

3. experimental

4. extra

5. xenon

IV. symbol

1. unknown quantity


a. times : by

b. hybrid

the license reads Dachshund x

a tall willow ( Salix x blanda ) developed in cultivation

: hybridity

c. out of

a litter by a grade sire x a scrub dam

3. capitalized

[from the Greek letter X]

Christ : Christian

4. power of magnification

5. capitalized reactance

6. abscissa

7. crossed with

8. kiss

9. a playing card of low rank

10. capitalized chemical group — used especially of a univalent anion or typically univalent negative radical (as halogen) in general formulas

11. the person in question — used especially by an illiterate in place of a signature

12. the place in question — used on a map or picture

13. — used to indicate choice or approval (as on a ballot)

V. ˈeks adjective

Usage: usually capitalized

of a motion picture : of such a nature that admission is denied to persons under a specified age (as 17) — used before the adoption of NC-17

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.