A prefix is a letter or group of letters, for example 'un-' or 'multi-', which is added to the beginning of a word in order to form a different word. For example, the prefix 'un-' is added to 'happy' to form 'unhappy'.
N-COUNT
前置代码（置于一组号码前的数字或字母，表示所属区域等）
A prefix is one or more numbers or letters added to the beginning of a code number to indicate, for example, what area something belongs to.