Manipravalam

Manipravalam was a literary style used in medieval liturgical texts in South India, which was composed in the curious mixture of Sanskrit and Malayalam which is referred to as Manipravalam, mani meaning ruby (Malayalam) and pravalam meaning coral (Sanskrit).

Lilathilakam, a work on grammar and rhetoric, written in the last quarter of the 14th century discusses the relationship between Manipravalam and Pattu as poetic forms. It lays special emphasis on the types of words that blend harmoniously. It points out that the rules of Sanskrit prosody should be followed in Manipravalam poetry. This particular school of poetry was patronized by the upper classes, especially the Nambudiris. It is also to be remembered that the composition of this dialect also reflects the way Aryan and Dravidian cultures were moving towards a synthesis. 
Dramatic performances given in Koothampalams, known by the names of Koothu and Koodiyattom, often used Sanskrit and Malayalam. In Koodiyattom, the clown (vidooshaka) is allowed to use Malayalam while the hero recites slokas in Sanskrit. Tholan, a legendary court poet in the period of the Kulasekhara kings, is believed to have started this practice. The language of Kramadeepikas and Attaprakarams, which lay down the rules and regulations for these dramatic performances, is considerably influenced by the composite literary dialect of Manipravalam.

Source: www.prd.kerala.gov.in/manipravalam.htm