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

円寂[enjaku] nirvana
閑寂[kanjaku] quiet
寂しがる[sabishigaru] to miss someone
寂れる[sabireru] to decline (in prosperity)
寂りょう[sekiryou] loneliness

心寂しい[kokorosabishii] lonely
静寂[seijaku] silence
入寂[nyuujaku] death of a priest
幽寂[yuujaku] quiet

おけさ節[okesabushi] style of Japanese folk song associated with Niigata Prefecture
双節棍[nunchaku] nunchaku (two linked fighting sticks)
一音節[ichionsetsu] monosyllable
一節切り[hitoyogiri] one-jointed bamboo musical instrument
音節[onsetsu] syllable

鰹節[katsubushi] katsuobushi
環節[kansetsu] segment (of worm)
関節[kansetsu] joints (knee joint, elbow joint, etc.)
関節リューマチ[kansetsuryuumachi] rheumatoid arthritis
関節炎[kansetsuen] arthritis