In Greek and Latin metre, brevis in longo (/ˈbrɛvɪs ɪn ˈlɒŋɡoʊ/; Classical Latin: [ˈbrɛwɪs ɪn ˈlɔŋɡoː]) is a short syllable at the end of a line that is counted as long. The term is short for (syllaba) brevis in (elemento) longo, meaning "a short [syllable] in a long [element]". Although the phenomenon itself has been known since ancient times, the phrase is said[1] to have been invented by the classical scholar Paul Maas.[2]
Brevis in longo is possible in various classical metres that require a long syllable at the end of a line, including dactylic hexameters and iambic trimeters. It can also be found in the centre of a line in some metres, before a dieresis (e.g. in the iambic octonarius). However, it does not seem to be found in every metre. For example, in Greek, in ionic metres ending in u u – –, there do not seem to be any examples.[1]
A similar phenomenon is found in other languages whose poetic metres are quantitative, such as Arabic, Persian, and Sanskrit.
Brevis in longo is associated with catalexis (the shortening of a metre by one syllable), in that when a metre ending u – loses its final syllable, the former short penultimate element becomes long since it is now final.
Brevis in longo is distinct from the metrical element anceps, which is a position in a line which can be filled by either a long or a short syllable. These two phenomena are often confused but there are differences between the two. For example, an anceps will be considered short or long in accordance with its natural length. A brevis in longo, on the other hand, will always be considered long, even though its natural quantity is short: the pause at the end of the line adds weight enough for even a short syllable to be counted as long.