In the English language, kasha is a term for the pseudocereal buckwheat. In Central and Eastern Europe, especially in Russia, Ukraine and Poland, kasha is a dish made of any kind of grains boiled in water or milk, possibly with additives, i.e., a porridge.

The largest gross consumption per capita is in Russia, with 15 kg (33 lb) per year, and Ukraine, with 12 kg (26 lb) per year. The share of buckwheat in the total consumption of cereals in Russia is 20%.

This English-language usage probably originated with Jewish immigrants, as did the form קאַשי kashi (technically plural, literally translated as "porridges").

The word generally refers to roasted whole-grain buckwheat or buckwheat groats. Notwithstanding in Slavic Europe, it refers to porridge in general and can be made from buckwheat or any cereal wheat, barley, oats, millet and rye. At least 1,000 years old, kasha is one of the oldest known dishes in Central European and Eastern European cuisine.

In Russian, buckwheat is referred to formally as гречиха (grechikha) and buckwheat grain and buckwheat groats as гречневая крупа (grechnevaya krupa). Informally buckwheat grain and buckwheat groats are called гречка (grechka), and the porridge made from buckwheat groats is known as гречневая каша (grechnevaya kasha). In Polish, buckwheat porridge is referred to as kasza gryczana. Annual (2013) per capita consumption of groats in Poland is approx. 1.56 kg (3.4 lb) per year (130 g (4.6 oz) a month).

In Russian culture

Kasha is commemorated in the Russian saying "щи да каша – пища наша" (shchi da kasha – pishcha nasha) literally "shchi and kasha are our food" or, more loosely, "cabbage soup and porridge are our kind of food".

Kasha can be used at any meal, either as a dish in itself, or a side dish.

In Jewish culture

As an Ashkenazi-Jewish comfort food, kasha is often served with onions and brown gravy on top of bow tie pasta, known as Kasha varnishkes. Kasha is a popular filling for knishes and is at times included in matzah-ball soup.