越冬[ettou] passing the winter
夏炉冬扇[karotousen] summer fires and winter fans
旧冬[kyuutou] former winters
厳冬[gentou] severe winter
今冬[kontou] this winter

三冬[santou] three winter months
春夏秋冬[shunkashuutou] spring, summer, autumn (fall) and winter
初冬[shotou] early winter
真冬[mafuyu] midwinter
暖冬[dantou] mild winter

懐旧[kaikyuu] recalling the old days
旧ソ連[kyuusoren] former Soviet Union
旧悪[kyuuaku] past misdeeds
旧衣[kyuui] worn-out clothes
旧詠[kyuuei] ancient poems

旧怨[kyuuen] old grudge
旧縁[kyuuen] old relationship
旧恩[kyuuon] old favors
旧仮名遣[kyuukanazukai] former (i.e. before the post-WWII reforms) kana usage in writing the readings of kanji