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To become coated with a thin layer of ice. If the ground frosts over tonight, we'll have a much harder time digging into it tomorrow.
to become covered with frost. The windows had all frosted over in the night. The car windows frosted over.
To become covered with frost: The blades of grass frosted over in the cold night air.
mod. angry; annoyed. The clerk was really frosted over when I asked for a better one.