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Webster 1913 Edition

Noun.

An implement for cutting, trimming, or ornamenting the rim of anything, as the edges of pies, etc.; also, a reamer.

Knight.

rimmer ‎(plural rimmers)

An implement for cutting, trimming, or ornamenting the rim of anything, as the edges of pies, etc.
(vulgar, slang) One who performs a rim-job (anal-oral sex).
A mixture of confections, spices, and/or salt applied to the rim of a beverage glass or mug.