夏季休暇[kakikyuuka] summer vacation
季刊[kikan] quarterly (e.g. magazine)
季語[kigo] seasonal word (in haiku)
季候[kikou] season
季節[kisetsu] season

季節はずれ[kisetsuhazure] unseasonable
季節的[kisetsuteki] seasonal
季節風[kisetsufuu] seasonal winds
四季[shiki] four seasons
冬季[touki] (season of) winter

ひもじい思い[himojiiomoi] state of feeling hungry
成吉思汗[jingisukan] Japanese mutton and vegetable dish
意思決定機関[ishiketteikikan] decision-making body
意思[ishi] intention
意思決定[ishikettei] decision-making

意思表示[ishihyouji] declaration of intention
一思いに[hitoomoini] instantly
引込思案[hikkomijian] reserved
危険思想[kikenshisou] dangerous thoughts
旧思想[kyuushisou] old-fashioned idea