A sweet, creamy coating for cakes and cupcakes, usually made from sugar, butter, and other ingredients; also the ice crystals that form on cold surfaces.
From 'frost' (Old English 'forst,' related to 'freeze') plus the suffix '-ing.' The cake decoration meaning became popular in America in the 1800s.
The cake decoration got its name because it looks like actual frost or ice crystals on a surface—our brains see the white sugar coating and think of winter's frozen beauty!
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