WordNet records no synonym and no antonym for nod. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
express or signify by nodding
“He nodded his approval”
lower and raise the head, as to indicate assent or agreement or confirmation
“The teacher nodded when the student gave the right answer”
1 of the 7 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for nod.
Synonyms, antonyms and the broader and narrower relations for nod come from Princeton University’s WordNet. Full sources and licences.
sway gently back and forth, as in a nodding motion
“the flowers were nodding in the breeze”
be almost asleep
“The old man sat nodding by the fireplace”
a sign of assent or salutation or command
the act of nodding the head