From 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]