(亦作x)
(pl. Xs或X's)
1
- the twenty-fourth letter of the alphabet英语字母表中第二十四个字母。
1.1
- denoting the next after W in a set of items, categories, etc.X项, X类（一组项目、分类中的第二十四位）。
1.2
- denoting an unknown or unspecified person or thing未知（或未指明）的人（或物）：
there is nothing in the data to tell us whether X causes Y or Y causes X.
数据中并没有告诉我们是X引起Y还是Y引起X.
1.3
x
(used in describing play in bridge) denoting an unspecified card other than an honour用于描述桥牌的玩法小牌。
1.4
- （一般作x）the first unknown quantity in an algebraic expression, usually the independent variable（代数表达式中的）第一未知量; 变量。
- [ORIGIN: the introduction of x, y, and z as symbols of unknown quantities is due to Descartes （Géométrie, 1637）, who took z as the first unknown and then proceeded backwards in the alphabet.]
1.5
- （一般作x）denoting the principal or horizontal axis in a system of coordinates第一坐标轴, 横坐标轴：
in combination the x-axis.x轴。
2
- a cross-shaped written symbol, in particular:X记号, X符号, 尤指：
2.1
- used to indicate a position on a map or diagram（在地图或图表上用来标示位置的）X记号。
2.2
- used to indicate a mistake or incorrect answer（标示错误答案的）X号。
2.3
- used in a letter or message to symbolize a kiss（在书信或便条中代表亲吻的）X符号。
2.4
- used to indicate one's vote on a ballot paper（表示选票上投票的）X号。
2.5
- used in place of the signature of a person who cannot write（不会写字之人的）画押。
3
- a shape like that of a letter X.X形：
two wires in the form of an X
呈X形的两条电线
in combination an X-shaped cross.一个X形十字架。
4
- the Roman numeral for ten（罗马数字）十。
- films classified as suitable for adults only (replaced in the UK in 1983 by 18, and in the US in 1990 by NC-17)（电影）限成人观看（1983年英国用18代替这一标志, 1990年美国采用NC-17）。
N. Amer. informal <北美, 非正式>
- (the drug) Ecstasy.同
E CSTASY（指毒品）。