From Chanticleer Society

Any drink served over finely crushed ice.

This is a style of drink you don’t see very often anymore. Usually refers to cordials by themselves, but can refer to a mixed drink as well. You pour the drink into a glass that is filled with finely crushed ice, then stir it until a frosty sheet of ice forms on the outside of the glass. Sometimes the drink is strained into a second glass, the ice is emptied from the first glass, and then the drink is poured back into the first (ice frosted) glass.

For an example, see: