K'ao is composed of 老 lao old abbreviated, and an obsolete phonetic. It originally meant old; then it came to signify a dead father; now it is the common term for examination.

K'ao is composed of 老 lao old in its contracted form as radical, and 丂 ch'iao an obsolete word meaning vapour struggling to escape. Its original meaning was old (= lao), and, in addition to its common signification, it has also that of a deceased father.