Main definitions of X in English

: X1X2X3

X1

(also x)

noun

  • 1The twenty-fourth letter of the alphabet.

    • ‘X is the 24th letter of the alphabet and it's got me stumped.’
    • ‘The Latin X came from Chi, a letter invented by the Greeks who used it to represent the sound ks in the Western part of the country.’
    1. 1.1Denoting the next after W in a set of items, categories, etc.
      • ‘You give the variable operand one of the 4 names #W, #X, #Y, or #Z.’
      • ‘A participant may answer a multiple-choice question with either the letter answer (W, X, Y or Z) or the verbal answer; however, if the verbal answer is given, it must be exactly as indicated in the question.’
    2. 1.2Denoting an unknown or unspecified person or thing.
      ‘there is nothing in the data to tell us whether X causes Y or Y causes X’
      • ‘Discover how 'Mr X' built an online business making over $100,000 a month (mostly profit) in just 16 weeks.’
      • ‘A greater number of fresh vegetables are sold in City X than in City Y.’
      • ‘Regarding Mr. X's remarks about the Directorate of Operations' "pitiful management": I did describe in my article the problem of upwardly mobile mediocrity, but Mr. X is right to fault me for not hammering home the point.’
    3. 1.3(in describing play in bridge) denoting an unspecified card other than an honour.
      ‘East knows that declarer cannot hold a doubleton Qx’
      • ‘In this case we are comparing the chances of East having J-10-x, J-x, or 10-x.’
      • ‘If your doubleton suit is in the form of: K Q, K J, Q J, Q x, J x don't count both honor and Shape points.’
    4. 1.4The first unknown quantity in an algebraic expression, usually the independent variable.
      • ‘We express a relationship between two variables, which we will refer to as x and y, by stating the following: The value of the variable y depends upon the value of the variable x.’
      • ‘For the quadratic function y=X^ - 9, determine the values of X such that y>or equal to 7.’
    5. 1.5Denoting the principal or horizontal axis in a system of coordinates.
      [in combination] ‘the x-axis’
      • ‘Click on the Options tab; then choose XY Plot and select the signal to be used for X coordinate generation in the X-Axis box.’
      • ‘When displaying two variables in a time domain plot, the X-axis is labeled with units of time.’
  • 2A shape like that of a letter X.

    ‘two wires in the form of an X’
    [in combination] ‘an X-shaped cross’
    • ‘The design of the Exofit safety harness uses a single piece of material constructed in the shape of an "X" that wraps around the worker.’
    • ‘Way back in the days of snail mail, teenagers would put an X across the envelope seal of a love letter to discourage the courier (usually a friend) from opening the envelope to take a peek (there was no guarantee that the envelope could be re-sealed with the X accurately realigned).’
    • ‘As a compromise, management marked each of the Idles' hands with a large black "X" as a warning to the club's staff not to serve alcohol to the band.’
    • ‘Also there were two paragraphs edited out with XXX's over them which were not initialed by either of us.’
    • ‘These conditions are normally very difficult to achieve, but we can reproduce these conditions by using two (or more) fine wires arranged so that they cross and touch at a single point, in the form of an X, as the load of a pulsed power generator.’
  • 3A cross-shaped written symbol, in particular.

    1. 3.1Used to indicate a position on a map or diagram.
      ‘put an X on the spot where you think its eye should be’
      • ‘In Sweden, X is used by the armed forces on maps to denote that blasting or other type of destruction has been prepared.’
      • ‘The students are to use the map to find the sites marked with an X.’
      • ‘The landing site, marked by a red "X", is located at 192.3 degrees west, 10.3 degrees south.’
      • ‘If you happen to camp just North of the straight trail section, the only way to accurately place the X on the map is to use a GPS.’
    2. 3.2Used to indicate a mistake or incorrect answer.
      • ‘I put a check next to correct problems and an X by incorrect problems.’
      • ‘Mark incorrect responses with an X.’
    3. 3.3Used in a letter or message to symbolize a kiss.
      • ‘Take care, love, Raffa xxx’
      • ‘Have a lovely day! xxxxx’
    4. 3.4Used to indicate one's vote on a ballot paper.
      ‘with trembling hand you inscribe your X on the slip of paper’
      • ‘Voters mark an 'X' in the first column for their first choice and a second 'X' in the second column for their other choice.’
      • ‘In order to vote you simply put an 'X' next to the name of the candidate you support.’
    5. 3.5Used in place of the signature of a person who cannot write.
      ‘nearly all those engaged in the fur trade signed with an X’
      • ‘When a person is physically unable to sign his or her name on the voter registration form, he or she may mark an X or take an oath swearing to the statement on the form.’
      • ‘In many jurisdictions testators may authenticate their last will and testament with the letter X’
      • ‘In other states the law requires courts to invalidate wills that are signed with an X unless the testator was physically or mentally incapable of signing her full name.’
  • 4The Roman numeral for ten.

    • ‘IX means to subtract I from X, leaving 9.’
    • ‘So XXXI is 31, and XXIV is 24.’
    • ‘These inscriptions allow us to demonstrate the presence of seven cohorts of the legion, either in whole or part, building on Hadrian's Wall: cohorts I, II, III, VI, VII, VIII and X.’
    • ‘One theory maintains that only the centurions of the first cohort, the so-called primi ordines, had different ranks, while the centurions of cohorts II-X all ranked equally.’

Pronunciation:

X

/ɛks/

Main definitions of X in English

: X1X2X3

X2

  • Films classified as suitable for adults only (replaced in the UK in 1983 by 18, and in the US in 1990 by NC–17).

Pronunciation:

X

/ɛks/

Main definitions of X in English

: X1X2X3

X3

North american
informal
  • The drug Ecstasy.

    • ‘Many of the users reported that, since "X" only lasts 4 to 5 hours, it brought them the feeling they wanted, and yet they were still able to control themselves unlike with other drugs such as LSD which has a longer duration.’
    • ‘They also appreciated that using "X" took them away from normal everyday problems.’
    • ‘I had just turned 18 and we went to a dance club, and my friends all got some "X".’

Pronunciation:

X

/ɛks/