The opening line 寒蝉凄切 (hánchán qīqiè, 'cold cicadas crying mournfully') is from Liu Yong's 《雨霖铃》, one of the most famous farewell ci poems of the Song dynasty — an anchor for 凄切 in literary Chinese.
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Literary, mostly used in writing or poetry — for spoken Chinese 'sad/mournful', 悲伤 (bēishāng) or 凄凉 (qīliáng) are more common.
