Longman Dictionary of Contemporary English
Douglas Harper's Etymology Dictionary
Wiktionary
vb. 1 (context transitive English) To keep or preserve for the winter. 2 (context intransitive English) To spend the winter (in a particular place).
Wikipedia
Overwinter (2010) is a werewolf novel by David Wellington. It is the sequel to his previous werewolf novel Frostbite, though this novel is only available in print; it was not first published online like some of his other novels.
Usage examples of "overwinter".
Inside this case, which overwinters attached to a twig or a piece of bark, fifty to four hundred eggs lie cushioned within air bubbles.
But they had every reason to discourage us from overwintering there, and from searching the island in the spring.
There would be little growing now, only a few sturdy herbs and the overwintering things like carrots and onions and turnips, but it made no difference.