A literary language is a register or dialect of a language that is used in literary writing of the language. This may also include liturgical writing. A literary variety of a language often gives rise to a standard variety of the language. The difference between literary and non-literary forms is more marked in some languages than in others. Where there is a strong divergence, the language is said to exhibit diglossia.
In Latin, Classical Latin was the literary register used in writing from 75 BC to the 3rd century AD, while Vulgar Latin was the common, spoken variety used across the Roman Empire. The Latin brought by Roman soldiers to Gaul, Iberia, or Dacia was not identical to the Latin of Cicero, and differed from it in vocabulary, syntax, and grammar. Some literary works with low-register language from the Classical Latin period give a glimpse into the world of early Vulgar Latin. The works of Plautus and Terence, being comedies with many characters who were slaves, preserve some early basilectal Latin features, as does the recorded speech of the freedmen in the Cena Trimalchionis by Petronius Arbiter. At the third Council of Tours in 813, priests were ordered to preach in the vernacular language—either in the rustica lingua romanica (Vulgar Latin), or in the Germanic vernaculars—since the common people could no longer understand formal Latin.