
1) Acknowledge silently 2) Acquiesce 3) Act drowsy 4) Affirmation 5) Affirmation of a sort 6) Affirmative act 7) Affirmative action 8) Affirmative gesture 9) Affirmative head motion 10) Affirmative signal 11) Agree physically 12) Agree silently 13) Agree to deny defence 14) Agree to disagree as defence 
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https://www.crosswordclues.com/clue/nod

1) Agreement 2) Assent 3) Bid 4) Command 5) Cue 6) Dozeoff 7) Dropoff 8) Drowse 9) Gesticulate 10) Go ahead 11) Nutation 12) Prompt 13) Sign 14) Stoop 
Found on 
https://www.crosswordclues.com/clue/nod
 [gesture]
[gesture]  A nod of the head is a gesture in which the head is tilted in alternating up and down arcs along the sagittal plane. In many cultures, it is most commonly, but not universally, used to indicate agreement, acceptance, or acknowledgment. ==Nodding to indicate acceptance== Different cultures assign different meanings to the gesture. ...
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http://en.wikipedia.org/wiki/Nod_(gesture)

• (v. t.) To incline or bend, as the head or top; to make a motion of assent, of salutation, or of drowsiness with; as, to nod the head. • (v. i.) To incline the head with a quick motion; to make a slight bow; to make a motion of assent, of salutation, or of drowsiness, with the head; as, to nod at one. • (v. t.) To cause to bend. &b...
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http://thinkexist.com/dictionary/meaning/nod/

National Organization on Disability
Found on 
http://www.encyclo.co.uk/local/20895

Lowering of head. To win by a nod, a horse extends its head with its nose touching the finish line ahead of a close competitor.
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http://www.encyclo.co.uk/local/21627
 Nod  intransitive verb
Nod  intransitive verb [ Middle English 
 nodden ; confer Old High German 
 kn...t...n , ge
 nuot...n , to shake, and English 
 nudge .] 
 1.  To bend or incline the upper part, with a quick motion; as, 
 nodding plumes.  
 2.  To incline the head with a quick motion...
Found on 
http://www.encyclo.co.uk/webster/N/26
 Nod  noun   1.
Nod  noun   1.  A dropping or bending forward of the upper part or top of anything. « Like a drunken sailor on a mast, Ready with every 
 nod to tumble down.» 
 Shak.   2.  A quick or slight downward or forward motion of the head, in assent, in familiar salutation, in ...
Found on 
http://www.encyclo.co.uk/webster/N/26
 Nod  transitive verb
Nod  transitive verb [ 
 imperfect & past participle   Nodded ; 
 present participle & verbal noun   Nodding .] 
 1.  To incline or bend, as the head or top; to make a motion of assent, of salutation, or of drowsiness with; as, to 
 nod ...
Found on 
http://www.encyclo.co.uk/webster/N/26

Nod is British slang for go-ahead, approval.
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http://www.probertencyclopaedia.com/browse/ZN.HTM

[
n] - the act of nodding the head 2. [n] - a sign of assent or salutation or command 3. [v] - sway gently back and forth, as of flowers or tress in the wind 4. [v] - express or signify by nodding 5. [v] - lower and raise the head, so as to indicate assent 6. [v] - let the head fall forward through drowsiness 7. [v] - ...
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http://www.webdictionary.co.uk/definition.php?query=nod
 noun
 noun the act of nodding the head
Found on 
https://www.encyclo.co.uk/local/20974
  No exact match found.