X1
(also x)
¦ noun (plural Xs or X's)
1. the twenty-fourth letter of the alphabet.
2. denoting the next after W in a set of items, categories, etc.
3. denoting an unknown or unspecified person or thing.
4. (usu. x) the first unknown quantity in an algebraic expression.
denoting the principal or horizontal axis in a system of coordinates.
5. a cross-shaped written symbol, used:
to indicate a position on a map.
to indicate an incorrect answer.
to symbolize a kiss.
to indicate one's vote on a ballot paper.
6. the Roman numeral for ten.
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X2
¦ symbol films classified as suitable for adults only (replaced in the UK in 1983 by 18, and in the US in 1990 by NC-17).
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X3
¦ abbreviation N. Amer. informal the drug Ecstasy.