次经（又称为次正经，Deuterocanonical Books，区别于“首正经”，Protocanonical Books；原文有隐藏、隐密的意思，引申为「神秘经典」之意。翻成英文是 secondary scripture 即第二正典）是指几部存在于希腊文七十士译本但不存在于希伯来文圣经的著作。或称为旁经、后典或外典。一般认为，这些著作是犹太教抄经士在后期加入，或在翻译的过程里纳入正典。但是也有几卷的亚兰文和希伯来文的抄本在死海古卷中被发现。次经不同于伪经，伪经的内容被正统神学认是否定基督的救恩，或与圣经教义相违背，或令基督教信仰动摇；而次经只是未被纳为基督教认可为旧约正典的犹太教著作。

Deuterocanonical books (literally meaing a second principal, rule, or criterion) is a term used since the 16th century in the Catholic Church and Eastern Christianity to describe certain books and passages of the Christian Old Testament that are not part of the current Hebrew Bible. The term is used in contrast to the protocanonical books, which are contained in the Hebrew Bible. This distinction had previously contributed to debate in the early Church about whether they should be classified as canonical texts. The term is used as a matter of convenience by the Ethiopian Orthodox Tewahedo Church and other Churches to refer to books of their Old Testament which are not part of the Masoretic Text.