x

1 of 5

noun

ˈeks 

plural x's or xs ˈek-səz 

often capitalized, often attributive

1

a

: the 24th letter of the English alphabet

b

: a graphic representation of this letter

c

: a speech counterpart of orthographic x

2

: ten see Table of Numbers

3

: a graphic device for reproducing the letter x

4

: one designated x especially as the 24th in order or class, or the first in an order or class that includes x, y, and sometimes z

5

: an unknown quantity

6

: something shaped like or marked with the letter X

x

2 of 5

verb

x-ed also x'd or xed ˈekst  ; x-ing or x'ing ˈek-siŋ 

transitive verb

1

: to mark with an x

2

: to cancel or obliterate with a series of x's

—usually used with out

x-ed out the mistake

x

3 of 5

abbreviation

1

cross

2

ex

3

experimental

4

extra

x

4 of 5

symbol

1

a

times

2 x 3 = 6

The picture was enlarged 3x [=enlarged to three times the original size].

b

by

—used in measurements

an 8x11 sheet of paper

An early 20th century Persian Hamadan Gallery carpet with a camel hair ground, measuring 10.10 x 5.5.

—The Magazine Antiques

2

by

—used in nonmathematical constructions

He drove a 4x4 vehicle.

X

5 of 5

adjective

ˈeks 

of a motion picture

: of such a nature that admission is denied to persons under a specified age (such as 17)

—used before the adoption of NC-17

Did you know?

Words Starting With X

Browse 436 words and phrases that start with the letter X, from Xanadu to xystus.

Synonyms

Verb

• blue-pencil
• cancel
• cross (out)
• dele
• delete
• edit (out)
• elide
• kill
• scratch (out)
• strike (out)
• stroke (out)

Examples of x in a Sentence

Noun

a word that starts with an x

a word that starts with x

Verb

x out the names of the people who have already left

Word History

First Known Use

Noun

before the 12th century, in the meaning defined at sense 1a

Verb

circa 1849, in the meaning defined at sense 1

Adjective

1970, in the meaning defined above

Phrases Containing x

• x-axis
• x-coordinate
• x-height
• x-intercept
• x-irradiation
• x out
• x-radiation
• x-ray
• x-section

Kids Definition

x

1 of 3 noun

ˈeks 

often capitalized

1

: the 24th letter of the English alphabet

2

: ten in Roman numerals

3

: an unknown quantity

x

2 of 3 verb

x-ed also x'd or xed ˈekst  ; x-ing or x'ing ˈek-siŋ 

1

: to mark with an x

2

: to cancel with a series of x's

X

3 of 3 adjective

ˈeks 

of a motion picture

: of such a nature that admission is denied to persons under a certain age (as 17)

—used before the adoption of NC-17

Medical Definition

x

1 of 2 noun

ˈeks 

plural x's or xs or x'es or xes ˈek-səz 

: the basic or monoploid number of chromosomes of a polyploid series : the number contained in a single genome compare n sense 1

x

2 of 2 symbol

1

capitalized halogen atom

—used in general formulas (as of trihalomethane CHX₃)

2

power of magnification

Legal Definition

x

1 of 2 noun

ˈeks 

often capitalized

1

: a mark used in place of a signature when the maker is incapable of signing his or her name (as because of illiteracy or a physical ailment)

2

: a mark used in indicating a choice or applicable item (as on an insurance form)

x

2 of 2 abbreviation

1

ex-distribution

2

ex-dividend

3

ex-rights

4

ex-warrants