nod

Etymology

From Middle English nodden, probably from an unrecorded Old English *hnodian (“to nod, shake the head”), from Proto-Germanic *hnudōną (“to beat, rivet, pound, push”), from Proto-Indo-European *kendʰ-, from *ken- (“to scratch, scrape, rub”). Compare Old High German hnotōn (“to shake”), hnutten (“to shake, rattle, vibrate”) (> modern dialectal German notteln, nütteln (“to rock, move back and forth”)), Icelandic hnjóða (“to rivet, clinch”).

verb

1. (transitive, intransitive) To incline the head up and down, as to indicate agreement.
2. (transitive, intransitive) To briefly incline the head downwards as a cursory greeting.
3. (transitive, intransitive) To sway, move up and down.
   Frail snowdrops that together cling / and nod their helmets, smitten by the wing / of many a furious whirl-blast sweeping by. 1819, William Wordsworth, On Seeing a Tuft of Snowdrops in a Storm
4. (intransitive) To gradually fall asleep.
5. (transitive) To signify by a nod.
   They nodded their assent.
6. (intransitive) To make a mistake by being temporarily inattentive or tired
   Even Homer nods.
7. (transitive, intransitive, soccer) To head; to strike the ball with one's head.
   Jones nods the ball back to his goalkeeper.
   With the hosts not able to find their passes - everything that went forward was too heavy or too short - Terry once again had to come to his side's rescue after Davies had brilliantly nodded into the path of Elmander, who followed up swiftly with a deflected shot. December 29, 2010, Chris Whyatt, “Chelsea 1 - 0 Bolton”, in BBC
8. (intransitive, figurative) To allude to something.
   Though the title nods to the Italian neo-realist classic Bicycle Thieves—and Cyril, much like the father and son in that movie, spends much of his time tracking down the oft-stolen possession—The Kid With A Bike isn’t about the bike as something essential to his livelihood, but as his sole connection to the freedom and play of childhood itself. March 15 2012, Soctt Tobias, The Kid With A Bike [Review]
9. (intransitive, slang) To fall asleep while under the influence of opiates.

noun

1. An instance of inclining the head up and down, as to indicate agreement, or as a cursory greeting.
2. A reference or allusion to something.
   Much like Mirror Mirror, Huntsman appears to borrow liberally from other fantasy films. Sometimes the nods are clever—Stewart’s first night in the forest, among hallucinatory fog that gives the trees faces and clutching hands, evokes Disney’s animated Snow White And The Seven Dwarfs from 1937. May 31, 2012, Tasha Robinson, “Film: Review: Snow White And The Huntsman”, in (Please provide the book title or journal name)
3. A nomination.
   For the fifth time in her career she received a Grammy nod, she has yet to win the award.
   Allen Gregory DeLongpre: Really putting a damper on the ol' Tony nod. 2011 Allen Gregory, "Pilot" (season 1, episode 1)
4. (figurative) Approval.
   The plan is expected to get the nod from councillors at the next meeting.
   Has the BRB received a secret nod from the Ministry to continue the LMR electrification from Weaver Junction to Glasgow? 1964 August, “News and Comment: One main line to Scotland?”, in Modern Railways, page 86