WordNet records no synonym and no antonym for hibernation. 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.
the torpid or resting state in which some animals pass the winter
cessation from or slowing of activity during the winter; especially slowing of metabolism in some animals
the act of retiring into inactivity
“he emerged from his hibernation to make his first appearance in several years”
Synonyms, antonyms and the broader and narrower relations for hibernation come from Princeton University’s WordNet. Full sources and licences.