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. Some grain whiskies also contain malted barley. Grain whiskies are manufactured primarily for blending with malt whisky to create blended whiskies. They are released as "Single Grain whisky" or "Blended Grain whisky" in Scotland.
Here I put all whiskies in my collection included grain alcohol on the labels.