1. 英语字母表的第24个字母
X is the twenty-fourth letter of the English alphabet.
2. （用于度量单位间）表示“乘以”
When writing down the size of something, you can use x in between the measurements to mean 'by'.
3. （用于表示不知道或不愿透露的人名）某，X
X can be used to represent the name of a person when you do not know their real name, or when you are trying to keep their real name a secret.
4. （用于表示不确定或无需指明的数量）
You can use X or x to refer to a number or amount when you do not know exactly how much it is, or when this information is not important.
5. （用于书信或书面留言末尾，表示亲吻）
x is used to represent a kiss at the end of a letter or written message.
6. （用于在地图上标明确切方位）
People sometimes write X on a map to mark a precise position that they want to refer to.