In ancient Greek and Latin literature, the trochaic septenarius (also known as the trochaic tetrameter catalectic) is a form of ancient poetic metre first used in 7th century BC Greek literature. It was one of the two most common metres of Roman comedy of the early 1st century BC and was also used for the marching songs sung by soldiers at Caesar's victory parade. After a period when it was little used, it is found again in the Pervigilium Veneris (variously dated to between 2nd and 5th century AD), and taken up again as a metre for Christian hymns. The same metre, with stress-rhythm replacing quantitative metre, has continued to be used, especially for hymns and anthems, right up to the present day.
The Ancient Greeks called poems in this metre simply "tetrameters", while the name "trochaic septenarius" (or plural "trochaic septenarii") is used for Latin poems in the metre.
The basic metre consists of 15 syllables alternating strong and weak. The Greek version of the metre is as follows (where – = long, u = short, and x = an anceps syllable):
| – u – x | – u – x || – u – x | – u – |
The Latin form of the metre, as used in Roman comedy, was as follows:
| – x – x | – x – x || – x – x | – u – |
In Roman comedy it is very common for a long or anceps element to be resolved, that is, replaced by two short syllables, except at the end of the half line or line.
There is usually a dieresis (or break) in the middle of the line after the eighth element.