A planctus ("plaint") is a lament or dirge, a song or poem expressing grief or mourning.
It became a popular literary form in the Middle Ages, when they were written in Latin and in the vernacular (e.g., the planh of the troubadours).
The most common planctus is to mourn the death of a famous person, but a number of other varieties have been identified by Peter Dronke.
The earliest known example, the Planctus de obitu Karoli, was composed around 814, on the death of Charlemagne.
The earliest examples of music for planctus are found in tenth-century manuscripts associated with the Abbey of Saint Martial of Limoges.