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late 14c., from Old French fum "smoke, steam, vapor, breath," from Latin fumus "smoke, steam, fume" (source of Italian fumo, Spanish humo), from PIE *dheu- (cf. Sanskrit dhumah, Old Church Slavonic dymu, Lithuanian dumai, Old Prussian dumis "smoke," Middle Irish dumacha "fog," Greek thymos "spirit, mind, soul").
c.1400, "to fumigate," from Old French fumer, from Latin fumare "to smoke, steam," from fumus "smoke, steam, fume" (see fume (n.)). Figurative sense of "show anger" is first recorded 1520s. Related: Fumed; fumes; fuming.