What is a Samashti charanam?

As we all know, a carnatic song consists of three main parts, Pallavi being the first section of the song, anupallavi , the middle one and Charanam, the last section of the song. check Structure of a keerthanai for more details.

Coming to the term "Samashti charanam" or "Samashti Charana"
a Charanam (last section of the song) combined with the anupallavi.
It may have slow and faster speed sections, and is performed after the pallavi in the absence of an anupallavi.

An example of a krithi having samashti charanam is Sri guru guha composed by Muthuswamy Dikshitar who is a part of Trinity of Carnatic Music.