What is the name for whisky bottled directly from the cask without dilution?

Whisky bottled directly from the cask without dilution is described as cask strength.

Cask-strength whisky is bottled at, or close to, the alcohol concentration it has in the barrel. Producers may make small adjustments, such as filtering or correcting for measurement, but the defining idea is that water has not been added to reduce the whisky to a standard bottling strength.

Whisky loses alcohol and water during maturation through evaporation, commonly called the angel’s share. The final strength therefore varies between casks and can also change during aging. A cask-strength release may be considerably stronger than a standard 40- or 43-percent bottling.

Drinkers often add a few drops of water to cask-strength whisky. This does not make it cask strength; it simply changes the serving strength and can open different aromas. “Barrel proof” is a related American term, although legal definitions and production practices can differ.