Poitín, anglicized as poteen or potcheen, is a traditional Irish distilled beverage. Former common names for Poitín were "Irish moonshine" and "mountain dew". It was traditionally distilled in a small pot still and the term is a diminutive of the Irish word pota, meaning "pot". The Irish word for a hangover is póit. In accordance with the Irish Poteen/Irish Poitín technical file, it can only be made from cereals, grain, whey, sugar beet, molasses and potatoes.

Alcohol by volume is a standard measure of how much alcohol is contained in a given volume of an alcoholic beverage. It is defined as the number of millilitres (mL) of pure ethanol present in 100 mL of solution at 20 °C (68 °F). The number of millilitres of pure ethanol is the mass of the ethanol divided by its density at 20 °C (68 °F), which is 0.78945 g/mL. The alc/vol standard is used worldwide. The International Organization of Legal Metrology has tables of density of water–ethanol mixtures at different concentrations and temperatures.