Porridge or mush. Known since ancient times, it was originally made emmer (zeia), spelt (olyra), millet (kechri) or chestnut or chickpea flour.
It was the fuel that ran the conquering Roman legions, who called it puls or pulmentum, and hence polenta (πολέντα), still the most common word for it in the parts of Greece formerly occupied by the Venetians (the Ionian Islands, Patras and Crete). In the 17th century the Venetians introduced the corn meal, and now in Greece as well as in Italy, katsamaki is nearly always made out of corn.
In some parts of Greece it's known as μαμαλίγκα (mamalinga) or χαβίτς (chavits).
Image by Alexandra Guerson