v.
 (nods, nodding, nodded)
   - lower and raise one's head slightly and briefly, especially in greeting, assent, or understanding, or as a signal. 
▸signify or express in this way:
 he nodded his consent.
  ▸
(nod something through)
 informal approve something by general agreement and without discussion.
 ▸move one's head up and down repeatedly.
 - let one's head fall forward when drowsy or asleep. 
▸
(nod off)
 informal fall asleep.
 ▸make a mistake due to a momentary lack of attention. 
[with allusion to L. dormitat Homerus ‘even Homer nods’ (Horace Ars Poet. 359).]
 - Soccer  head (the ball) in a specified direction without great force.
 
n.
 an act of nodding. 
▸a gesture of acknowledgement or concession.
 
  Phrase
  
    - a nodding acquaintance
 a slight acquaintance.  - be on nodding terms
 know someone slightly.  - give someone/thing the nod
  - select or approve someone or something.
 - give someone a signal.
 
  - on the nod
 Brit. informal  - by general agreement and without discussion.
 - dated on credit.
 
 
   
  Etymology
  ME: perh. of Low Ger. origin.