The Collaborative International Dictionary of English v.0.48:

Hibernaculum \Hi`ber*nac"u*lum\, n. [See Hibernacle.]
   1. (Bot.) A winter bud, in which the rudimentary foliage or
      flower, as of most trees and shrubs in the temperate zone,
      is protected by closely overlapping scales.
      [1913 Webster]

   2. (Zool.) A little case in which certain insects pass the
      winter.
      [1913 Webster]

   3. Winter home or abiding place. --J. Burroughs.
      [1913 Webster]