to cross out or mark with or as if with an x (often followed byout ).
to x out an error.
to indicate choice, as on a ballot or examination (often followed byin ).
to x in the candidate of your choice.
an unknown quantity or a variable.
the letter x used to replace or obscure a gender morpheme, as to avoid the -o or -a inflection of a word borrowed from Spanish or the sequence m-e-n in the word women . See Latinx, womxn.
the letter x indicating a variable and used to hold a place in a word or abbreviation that can be occupied by another letter, as in CxO to account for a range of specialized executive positions in a corporation, for example CEO , CFO , and COO .
(used at the end of letters, telegrams, etc., to indicate a kiss.)
(used to indicate multiplication) times.
8 × 8=64.
(used between figures indicating dimensions) by.
3″ × 4″ (read: “three by four inches”);
3″ × 4″ × 5″ (read: “three by four by five inches”).
power of magnification.
a 50x telescope.
(used as a signature by an illiterate person.)
cross.
crossed with.
(used to indicate a particular place or point on a map or diagram).
X marks the spot where the pirates' treasure is buried.
out of; foaled by.
a colt by Flag-a-way x Merrylegs.
(used to indicate choice, as on a ballot, examination, etc.)
(used to indicate an error or incorrect answer, as on a test.)
Mathematics. (in Cartesian coordinates) the x-axis.
Chess. captures.
a person, thing, agency, factor, etc., of unknown identity.
I feel sorry for poor Mr. X, the man she will ultimately marry.
the 24th letter of the English alphabet, a consonant.
any spoken sound or combination of sounds represented by the letter X or x, as in xylene, box, or exact.
something having the shape of an X .
a written or printed representation of the letter X or x.
a device, as a printer's type, for reproducing the letter X or x.
experimental.
extra.
extraordinary.
the 24th in order or in a series.
(sometimes lowercase) the Roman numeral for 10.
Christ.
Christian.
cross.
Electricity. reactance.
Slang. a ten-dollar bill.
(no longer in official use by the Motion Picture Association of America) a rating for movies with subject matter that is suitable for adults only.
(in Great Britain) a designation for a film recommended for adults only.
a person, thing, agency, factor, etc., of unknown identity.
Chemistry. (formerly) xenon.
indicating a film that may not be publicly shown to anyone under 18. Since 1982 replaced by symbol 18
( as modifier )
an X film
denoting any unknown, unspecified, or variable factor, number, person, or thing
(on letters, cards, etc) denoting a kiss
(on ballot papers, etc) indicating choice
(on examination papers, etc) indicating error
for Christ; Christian
ten See Roman numerals
commerce banking finance ex
maths the x- axis or a coordinate measured along the x- axis in a Cartesian coordinate system
an algebraic variable
the 24th letter and 19th consonant of the modern English alphabet
a speech sound sequence represented by this letter, in English pronounced as ks or gz or, in initial position, z, as in xylophone
First recorded in 1840–50
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Writing on X on Monday evening, Carns said the arson attacks and subsequent disinformation campaign showed the UK needed to rethink its approach to defence.
From BBC • Jun. 16, 2026
Most of the respondents visited X or YouTube specifically to find news.
From Barron's • Jun. 15, 2026
Appeared in the June 16, 2026, print edition as 'Notable & Quotable: Nix on X'.
From The Wall Street Journal • Jun. 15, 2026
On Saturday, Strickland posted on X that he wanted to attend the fan fest on the Ellipse.
From Los Angeles Times • Jun. 15, 2026
The Gran gestured for the Spares to come forward, and as they stood there lined up, she made a giant X over their heads, magic to seal the contract until the impossible task began.
From "Witchlings" by Claribel A. Ortega
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
