nod

v. (-dd-) 1 incline one's head slightly and briefly in assent, greeting, or command. 2 let one's head fall forward in drowsiness; be drowsy. 3 incline (one's head). 4 signify (assent etc.) By a nod. 5 (of flowers, plumes, etc.) Bend downwards and sway. 6 make a mistake due to a momentary lack of alertness or attention. n. Nodding of the head.  nod off colloq. Fall asleep. [origin unknown]

v. i. To bend or incline the upper part, with a quick motion; as, nodding plumes.