0 to move your head up and down as a way of agreeing -- fare cenno col capo
1 to make a quick forward and downward movement of the head to show agreement, as a greeting etc -- (fare un cenno col capo)
2 to let the head fall forward and downward when sleepy -- sonnecchiare
Grandmother sat nodding by the fire.
3 a nodding movement of the head -- (cenno del capo)
He answered with a nod.