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.
The stock surged 20% Monday after Musk said the company could hit revenue of $1 trillion in a post on X over the weekend.
From Barron's • Jun. 16, 2026
On Nov. 13, before the indictment was unsealed, Adani congratulated Trump on his election and pledged in a X post to invest $10 billion in the U.S. and create 15,000 jobs here.
From The Wall Street Journal • Jun. 16, 2026
The government is yet to release the full list of platforms affected, but said YouTube, Facebook and X would also be included.
From BBC • Jun. 15, 2026
Eight rescue swimmers were deployed and pulled the two women from the water, Breton said in a video posted to X.
From Los Angeles Times • Jun. 15, 2026
A thin boy, wearing a Malcolm X T-shirt and sporting a DIY haircut, sat up from where he’d once been sprawled by a gaping hole in the side of the bus.
From "Tristan Strong Punches a Hole in the Sky" by Kwame Mbalia
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.
