This term describes a structure that is composed of a multinucleated cytoplasm. It is either the result of the fusion of multiple adjoining cells, or the formation (by division) of multiple nuclei in a large cell.

Since cardiac muscle is formed by separate cells that are anatomically, mechanically, chemically, and electrically connected, the cardiac muscle has been called a "functional syncytium". Functionally, cardiac muscle works as a unit.

For those interested in the etymology of the word [syncytium], it arises from the Greek and its components are the prefix [syn-], meaning "together"; the root term [-cyt-], meaning "cell"; and the suffix [-ium], meaning "layer" or "membrane"