Late Latin is the scholarly name for the form of written Latin of late antiquity. English dictionary definitions of Late Latin date this period from the 3rd to 6th centuries CE, and continuing into the 7th century in the Iberian Peninsula. This somewhat ambiguously defined version of Latin was used between the eras of Classical Latin and Medieval Latin. Scholars do not agree exactly when Classical Latin should end or Medieval Latin should begin.
Being a written language, Late Latin is not the same as Vulgar Latin, or more specifically, the spoken Latin of the post-Imperial period. The latter served as the ancestor of the Romance languages. Although Late Latin reflects an upsurge in the use of Vulgar Latin vocabulary and constructs, it remains largely classical in its overall features, depending on the author who uses it. Some Late Latin writings are more literary and classical, but others are more inclined to the vernacular. As such it is an important source of information about changes in the spoken language, while not being a simple replication of the state of the oral language at the time. Also, Late Latin is not identical to Christian patristic Latin, used in the theological writings of the early Christian fathers. While Christian writings used a subset of Late Latin, pagans, such as Ammianus Marcellinus or Macrobius, also wrote extensively in Late Latin, especially in the early part of the period.