Nod \Nod\, v. i. [OE. nodden; cf. OHG. kn?t?n, genuot?n, to shake, and E. nudge.]

1. To bend or incline the upper part, with a quick motion; as, nodding plumes.

2. To incline the head with a quick motion; to make a slight bow; to make a motion of assent, of salutation, or of drowsiness, with the head; as, to nod at one.

3. To be drowsy or dull; to be careless.

Nor is it Homer nods, but we that dream. --Pope.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Nod \Nod\, v. t. [imp. & p. p. Nodded; p. pr. & vb. n. Nodding.]

1. To incline or bend, as the head or top; to make a motion of assent, of salutation, or of drowsiness with; as, to nod the head.

2. To signify by a nod; as, to nod approbation.

3. To cause to bend. [Poetic]

By every wind that nods the mountain pine. --Keats.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Nod \Nod\, n.

1. A dropping or bending forward of the upper oart or top of anything.

Like a drunken sailor on a mast, Ready with every nod to tumble down. --Shak.

2. A quick or slight downward or forward motion of the head, in assent, in familiar salutation, in drowsiness, or in giving a signal, or a command.

A look or a nod only ought to correct them [the children] when they do amiss. --Locke.

Nations obey my word and wait my nod. --Prior.

The land of Nod, sleep.

Source: Webster's Revised Unabridged Dictionary (1913)