Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • The symbol for the Roman numeral 10.
  • A symbol for the word cross. Used in combination, as in Xing for crossing or motoX for motocross.
  • abbreviation Christ (Greek Χριστος, Khristos)
  • abbreviation Christian
  • abbreviation ex
  • abbreviation ex dividend
  • abbreviation experimental
  • abbreviation extra
  • abbreviation extreme
  • abbreviation extremely
  • noun A movie rating indicating that admission will not be granted to anyone under the age of 17.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun A hazard indicator, sometimes incorporated into standard labelling and signage systems
  • noun The twenty-fourth letter of the basic modern Latin alphabet.
  • noun The number 10.
  • noun A symbol of the IPA, representing a voiceless uvular fricative.
  • noun bowling strike
  • noun An unknown quantity or unknown value.
  • noun slang Ecstasy, a particular street drug.
  • noun The twenty-fourth letter of the English alphabet, called ex and written in the Latin script.
  • noun Any mark that looks like that letter, such as such a mark made by a person who cannot read or write, in lieu of a signature.
  • noun lacrosse The spot behind the goal.
  • abbreviation North America cross, crossing
  • abbreviation informal Christ
  • noun One of the tristimulus values which, with Y and Z, defines coordinates in a three-dimensional color space. Pronounced big X or cap X.
  • adjective Suitable only for those aged 16 or (later) 18 years and over.
  • adjective movie rating Obscene.

Etymologies

from Wiktionary, Creative Commons Attribution/Share-Alike License

Possibly from skull and crossbones

from Wiktionary, Creative Commons Attribution/Share-Alike License

Presumably by abbreviation of the pronunciation of ecstasy.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Christ by abbreviation, from Ancient Greek Χ (Ch, "(letter chi)"), from Χριστός (Christós, "Christ").

from Wiktionary, Creative Commons Attribution/Share-Alike License

As defined in CIE 1931 color space.

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Examples

  • (Note: There's no way the current version of iTunes 10 for Mac OS X-- which tramples over Apple's interface guidelines by arranging its window-close buttons vertically, not horizontally like a normal OS X app -- would pass muster under clause 10.3.)

    Apple offers App Store review guidelines (and updates iPhone software) 2010

  • (Note: There's no way the current version of iTunes 10 for Mac OS X-- which tramples over Apple's interface guidelines by arranging its window-close buttons vertically, not horizontally like a normal OS X app -- would pass muster under clause 10.3.)

    Apple offers App Store review guidelines (and updates iPhone software) 2010

  • By way of comparison, Apple has a habit of only supporting the current and previous version of OS X-- the 2005-vintage OS X 10.4 Tiger saw its last update in May 2009.

    Microsoft retires Windows 2000, Windows XP SP2 2010

  • Let's consider: Is it substantively meaningful that someone exposed to a violent videogame feels X% more aggressive in the aftermath, where X is a small but reliably non-zero number?

    MediaFX Sound and Fury 2010

  • A lot of fields have the problem that ever-smaller sub-sub-specialties operate in surprising isolation from other specialties, to the extent that two large bodies of expert consensus in areas that really ought to be related have developed so independently that they sometimes literally contradict each other: people in sub-field A take X as axiomatic, whereas people in related sub-field B studying similar issues take ~X as axiomatic.

    The Volokh Conspiracy » Too Smart to Become the Chess World Champion? 2010

  • By way of comparison, Apple has a habit of only supporting the current and previous version of OS X-- the 2005-vintage OS X 10.4 Tiger saw its last update in May 2009.

    Microsoft retires Windows 2000, Windows XP SP2 2010

  • Let's consider: Is it substantively meaningful that someone exposed to a violent videogame feels X% more aggressive in the aftermath, where X is a small but reliably non-zero number?

    March 2010 2010

  • This is justified on the grounds that principle X is a good thing and so therefore 0.5X is better than 0X, which is what happens when the other guy that believes ~X is elected.

    The Volokh Conspiracy » Jonathan Rauch on David Frum on the Conservative Movement 2010

  • Or what is the least bad solution if you take it as a given that everyone will get health insurance that covers X% of expenses above $X?

    Insurance as a Prisoners' Dilemma, Bryan Caplan | EconLog | Library of Economics and Liberty 2009

  • But certainly, it would be fair to say "the top X%" of the population in Net Worth is rich, and the bottom X % is poor.

    That's Rich! Steven Barnes 2008

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    January 2, 2010