Beixi ziyi 北溪字義 "Master North Stream's Meaning of Words" is a philosophical compendium written by the Southern Song-period 南宋 (1127-1279) scholar Chen Chun 陳淳 (1159-1223), courtesy name Anqing 安卿, style Beixi 北溪. He hailed from Longxi 龍溪 in the prefecture of Zhangzhou 漳州 (modern Zhangzhou, Fujian) and was a disciple of the Neo-Confucian master Zhu Xi 朱熹 (1130-1200) when the latter was prefect of Zhangzhou. In 1217, Chen Chun was appointed gentleman for meritorious achievements (digonglang 迪功郎) and then promoted to recorder (zhubu 主簿) in the district of Anxi 安溪 in the prefecture of Quanzhou 泉州, but he died before taking over this office. His posthumous title is Chen Wen'an 陳文安. His collected writings are called Beixi da quanqi 北溪大全集.
The 2-juan long book Beixi ziyi is also known under the names Ziyi xiangjiang 字義詳講, Sishu ziyi 四書字義 and Sishu xingli ziyi 四書性理字義. These titles point more directly at the content of the book, namely an explanation of the methods to study the Confucian Classics, particularly the Four Books (Sishu 四書). The main tool were Zhu Xi's collected commentaries Sishu zhangju jizhu 四書章句集注 and his book Jinsilu 近思錄. The Beixi ziyi is divided into 26 chapters that focus on one topic of Neo-Confucianism each, like the "Heavenly" given life (ming 命), the human character (xing 性), the mind (xin 心), emotions (qing 情), potential (cai 才), the will (zhi 志), intention (yi 意), the Confucian virtues kindheartedness (ren 仁), propriety (yi 義), wisdom (zhi智), trustworthiness (xin 信), loyalty (zhongxin 忠信), benevolence (zhongshu 忠恕), consistency (yiguan 一貫), sincerity (cheng 誠), respect (jing 敬), veneration (gongjing 恭敬), the Way (dao 道), the universal order (li 理), virtue (de 德), the Utmost Extension (taiji 太極), the middle harmony (zhonghe 中和), the middle way (zhongyong 中庸), rituals and music (liyue 禮樂), "standard methods and compulsion" (jingquan 經權), "Righteousness and personal profit" (yili 義利), ghosts and spirits (guishen 鬼神), and the intellectual opponents of Confucianism, namely Buddhism and Daoism. The titles of the chapters show that Chen Chun's book focus on the definitions and explanations of the core terms of Neo-Confucian philosophy, and therefore has the character of a kind of a handbook.
The Beixi ziyi includes an appendix called Yanling jiangyi 嚴陵講義 that is a record of the instructions that Chen Chun gave in 1216 during a journey when he dwelled in Yanling. It is divided into four chapters, namely Daoxue titong 道學體統 "The organic system of Confucian teachings", Shiyou yuanyuan 師友淵源 "The profound origins of amical relations between teacher and student", Yonggong jiemu 用工節目 "A program of practical application" and Dushu cidi 讀書次第 "The order of studying".
The Qing-period 清 (1644-1911) scholar Gu Xiuhu 顧秀虎 published a critical edition of the Beixi ziyi with an appendix (Buyi 補遺) that includes a collection of fragments from the book that are quotes in other texts, but are not to be found in the transmitted editions.