tertia

Tertia is a Latin feminine form meaning "the third." It functions as an adjective or noun in Latin, used to indicate the third position or part and to agree with feminine nouns. The root tert- comes from tertius, with the -ia ending yielding tertia in feminine form. In various languages influenced by Latin, forms such as terza or terza rima reflect the same "third" meaning.

In liturgical usage, Hora Tertia, also called Tertia or Terce, is the third canonical hour of the Divine Office in the Latin rite, observed around 9 a.m. The name Terce derives from the Latin root and is used in English-language and other Christian traditions as well.

Geology and related sciences have historical use of the term Tertiary, from tertius, to denote the period between the Cretaceous and Quaternary. In modern geology, the Tertiary is subdivided into the Paleogene and Neogene, and the term is less commonly used in formal classifications, though it remains familiar from older literature and some curricula.

Other uses include employing Tertia as a feminine given name in certain cultures. In Romance languages, related forms such as terza or terza rima in Italian highlight the same core meaning of “third,” appearing in phrases and naming conventions.

See also: tertiary, Terce, Hora Tertia, Terza.