Idiom refers to a phrase whose meaning is different from the meanings of each word considered separately. 习语，在英语中指那些意义不同于字面意义的固定短语，在汉语中指四字格成语。
An idiom is a phrase refined from a longtime use with the features of conciseness, metaphor and penetration, etc. 习语是经过长时间的使用而提炼出来的固定短语或短句，它一般具有文字简练，比喻形象，含义精辟等特点。
