: an official or standard collection of drug formulas and descriptions <a codex similar to the British Pharmaceutical Codex>
Manuscript book, especially of Scripture, early literature, or ancient mythological or historical annals. The earliest type of manuscript in the form of a modern book (i.e., a collection of pages stitched together along one side), the codex replaced earlier rolls of papyrus and wax tablets. Among its advantages, it could be opened at once to any point in the text, it permitted writing on both sides of the leaf, and it could contain long texts. The oldest extant Greek codex is the Codex Sinaiticus (4th century AD), a biblical manuscript. Codices were developed separately by pre-Columbian Mesoamericans after c. AD 1000.