The chemical symbol of xenon.In electricity, the symbol for reactance in alternating-current circuits.In wireless telegraphy, a local disturbance causing a false signal; a stray.The twenty-fourth letter and nineteenth consonant-sign in the English alphabet.As a numeral, X stands for ten.As an abbreviation, X. stands for Christ, as in Xn. (Christian), Xmas. (Christmas).As a symbol: In ornithology, in myological formulas, the symbol of the semitendinosus muscle.In mathematics:[lowercase] In algebra, the first of the unknown quantities or variables.[l. c] In analytical geometry, an abscissa or other rectilinear point-coördinate.In mechanics, the component of a force in the direction of the axis of x.Originally, a mark on brewers' casks; hence, a name given to ale of a certain quality. Compare XX, XXX.