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early 15c., "apply hot liquids," from Old French fomenter (13c.) "apply hot compress (to a wound)," from Late Latin fomentare, from Latin fomentum "warm application, poultice," contraction of *fovimentum, from fovere "to warm; cherish, encourage" (see fever). Extended sense of "stimulate, instigate" (1620s) was in the French. Related: Fomented; fomenting.