Abstract: There have been different interpretations of zuo jia坐甲wearing armor to watch for the enemy for a long time. Its definition in the dictionaries is not clear, either. This paper argues that the original meaning of zuo jia is wearing armor to watch for the enemy, rather than "sitting on armor". Therefore, different meanings are extended from the original meaning. Zuo jia does not mean zuo zhen 坐阵sitting array before attacking, either.