Origin and history of warmer

1892, baseball slang; see bench (n.) in the sporting sense + warmer (n.).

The days for "bench-warmers" with salaries are also past. [New York Sporting News, Jan. 9, 1892]

Old English had bencsittend "one who sits on a bench." Phrase warm the bench is sports jargon is attested by 1907.

1974, from leg (n.) + warmer (n.). Related: Leg-warmers.

Middle English warmen, from Old English wyrman "make warm" and wearmian "become warm;" from the root of warm (adj.). Related: Warmed; warming.

Warming-pan, "large, covered, long-handled pan full of live coals, for warming beds," is by 1570s.