名詞 nod:

1. a sign of assent or salutation or command
2. the act of nodding the head

動詞 nod:

1. express or signify by nodding
2. lower and raise the head, as to indicate assent or agreement or confirmation
3. let the head fall forward through drowsiness
4. sway gently back and forth, as is in a nodding motion
5. be almost asleep

1. The old lady sat nodding by the fire.
   那老太太坐在火爐旁打瞌睡。
2. She nodded when she passed me in the street.
   她在街上走過我身旁時向我點了點頭。
3. He nodded in agreement with me.
   他點頭表示同意我的意見。
4. She greeted us with a nod of the head.
   她向我們點點頭打招呼。

nod

v.（動詞）
nod.ded,nod.ding,nods
v.intr.（不及物動詞）
To lower and raise the head quickly, as in agreement or acknowledgment.
點頭：快速地低下并抬起頭，如表示同意或致意
To let the head fall forward when sleepy; doze momentarily:
打盹：當困倦時頭向前垂著；短時的小睡：
例句：
nodded off on the train.
在火車上打瞌睡

To be careless or momentarily inattentive as if sleepy; lapse:
過失：不小心或好象困了一時疏忽；失誤：
例句：
Even Homer nods.
即使荷馬也疏忽

To sway, move up and down, or droop, as flowers in the wind.
上下擺動：彎曲上下來回移動或垂下，如在風中的花朵
v.tr.（及物動詞）
To lower and raise (the head) quickly in agreement or acknowledgment.
點（頭等）：快速地低下并抬起（頭）以示同意或致意
To express by lowering and raising the head:
點頭表示：通過點頭表示：
例句：
He nodded his agreement.
他點頭表示同意

To summon, guide, or send by nodding the head:
點頭示意：通過點頭來召喚，指引或使去：
例句：
The chairperson nodded us into the room.
那位主席點頭示意將我們引進屋子

n.（名詞）
A forward or up-and-down movement of the head, usually expressive of drowsiness or agreement:
點頭：頭的向前或上下移動的動作，通常為困倦或同意的表達：
例句：
gave a nod of affirmation.
點頭確認

An indication of approval or assent:
同意：表示同意或贊成的信號：
例句：
The contestant got the nod from the judges.
選手從裁判那獲得了同意的信號

來源：
Middle English nodden ; akin to perhaps akin to Middle High German notten
中古英語 nodden ；類似于 可能類似于 中古高地德語 notten

【引伸】
nod.der
n.（名詞）