Definition of "Nod" :

noun: the act of nodding the head

noun: a sign of assent or salutation or command

verb: be almost asleep

"The old man sat nodding by the fireplace."

verb: let the head fall forward through drowsiness

"The old man was nodding in his chair."

verb: lower and raise the head, as to indicate assent or agreement or confirmation

"The teacher nodded when the student gave the right answer."

verb: express or signify by nodding

"He nodded his approval."

verb: sway gently back and forth, as in a nodding motion

"The flowers were nodding in the breeze."