the world > movement > motion in specific manner > alternating or reciprocating motion > move to and fro or up and down [verb (intransitive)] > nod the head > rapidly or repeatedly (3)
intransitive. To nod unsteadily to and fro; to nod the head rapidly and continuously. Also transitive: to nod (the head) up and down in this manner.
intransitive. To nod repeatedly, esp. as a sign of drowsiness.
intransitive. = niddle-noddle, v.