Source : Webster's Revised Unabridged Dictionary (1913)

Kotow \Ko*tow"\, n. [Chinese, knock head.]
   The prostration made by mandarins and others to their
   superiors, either as homage or worship, by knocking the
   forehead on the ground. There are degrees in the rite, the
   highest being expressed by three knockings. [China]

Kotow \Ko*tow"\, v. i. [imp. & p. p. {Kotowed}; p. pr. & vb. n.
   {Kotowing}.]
   To perform the kotow.

Source : WordNet®

kotow
     n : a former Chinese custom of touching the ground with the
         forehead as a sign of respect or submission [syn: {kowtow}]
     v : try to gain favor by cringing or flattering; "He is always
         kowtowing to his boss" [syn: {fawn}, {toady}, {truckle},
         {bootlick}, {kowtow}, {suck up}]