Wordnet 3.0
NOUN (1)
1.
the middle of winter;
The Collaborative International Dictionary of English v.0.48:
Midwinter \Mid"win`ter\, n. [AS. midwinter.]
The middle of winter. --Dryden.
[1913 Webster]
WordNet (r) 3.0 (2006):
midwinter
n 1: the middle of winter