What is "grain whisky"

n. Whisky made from unmalted barley mixed with maize or rye.

Grain whisky ordinarily refers to any whisky made, at least in part, from grains other than malted barley, such as whisky made using maize (corn), wheat or rye. Grain whiskies may also contain some malted barley (and are required to if produced in Scotland). Whisky made from only malted barley (or primarily from malted barley) is typically called malt whisky rather than grain whisky (although barley is a grain). Most American whiskeys and Canadian whiskys are grain-based.