A lot vs. Alot: 9 Grammatical Pitfalls
also kow-tow, 1804, from Chinese k'o-t'ou custom of touching the ground with the forehead to show respect or submission, literally "knock the head," from k'o "knock, bump" + t'ou "head." The verb in the figurative sense of "act in an obsequious manner" is from 1826. Related: Kowtowed; kowtowing.
in traditional China, the act of supplication made by an inferior to his superior by kneeling and knocking his head to the floor. This prostration ceremony was most commonly used in religious worship, by commoners who came to make a request of the local district magistrate, and by officials and representatives of foreign powers who came into the presence of the emperor. By the Ming period (1368-1644), the ritual, especially as made to the shrine of Confucius by the emperor and to the emperor by his officials and foreign envoys, involved "three kneelings and nine prostrations."