Kowtow

This word can be either a noun or a verb. In noun form kowtow is "The act of kneeling and touching the forehead to the ground" or "an obsequious act" (AHD). As a verb kowtow means "To kneel and touch the forehead to the ground in an expression of deep respect, worship, or submission, as formerly done in China" or alternately "to show servile deference" (AHD). The word itself comes to English directly from the Mandarin Chinese word, "kòu tóu" (AHD). Since "kòu" means to knock and "tóu" means head, the components of the Mandarin word imply its meaning--since a person performing the ritual touches his forehead to the floor, he literally knocks his head.