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[eks] /ɛks/
verb (used with object), x-ed or x'd
[ekst] /ɛkst/ (Show IPA),
x-ing or x'ing
[ek-sing] /ˈɛk sɪŋ/ (Show IPA)
to cross out or mark with or as if with an x (often followed by out):
to x out an error.
to indicate choice, as on a ballot or examination (often followed by in):
to x in the candidate of your choice.
Origin of x
First recorded in 1840-50 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for x out


noun (pl) x's, X's, Xs
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


(commerce, banking, finance) ex
(maths) the x-axis or a coordinate measured along the x-axis in a Cartesian coordinate system
an algebraic variable


(formerly, in Britain)
  1. indicating a film that may not be publicly shown to anyone under 18. Since 1982 replaced by symbol 18
  2. (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
(Roman numeral) ten See Roman numerals
Word Origin
(sense 6) from the form of the Greek letter khi (Χ), first letter of Khristos Christ
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Contemporary definitions for x out
verb phrase

to cross out; eliminate


I X'd out that plan.

Usage Note

slang's 21st Century Lexicon
Copyright © 2003-2014, LLC
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Word Origin and History for x out


most English words beginning in -x- are of Greek origin or modern commercial coinages. East Anglian in 14c. showed a tendency to use -x- for initial sh-, sch- (cf. xal for shall), which didn't catch on but seems an improvement over the current system. As a symbol of a kiss on a letter, etc., it is recorded from 1765. In malt liquor, XX denoted "double quality" and XXX "strongest quality" (1827).

Algebraic meaning "unknown quantity" (1660 in English), sometimes said to be from medieval use, originally a crossed -r-, probably from Latin radix (see root (n.)). Other theories trace it to Arabic, but a more prosaic explanation says Descartes (1637) took x, y, z, the last three letters of the alphabet, for unknowns to correspond to a, b, c, used for known quantities.

Used allusively for "unknown person" from 1797, "something unknown" since 1859. As a type of chromosome, attested from 1902 (first so called in German; Henking, 1891). First used 1950 in Britain to designate "films deemed suitable for adults only;" adopted in U.S. Nov. 1, 1968.

Online Etymology Dictionary, © 2010 Douglas Harper
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Slang definitions & phrases for x out

X 1


A person's signature: Just put your X on this and we're in business

[fr the custom of an illiterate person to make an X in place of a written signature]

X 2


Ecstasy, a variety of amphetamine narcotic (1990s+ Narcotics)


To use the narcotic ecstasy: Many of us have had the experience of being around someone who is X-ing

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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