Fuming was a war tactic said by the Vori to be employed by their enemies, the Kradin. According to Rafin, the Kradin had fumed his village. (VOY: "Nemesis")
Since the Vori employed idiosyncratic language, this term might refer to a familiar kind of practice, for example chemical warfare. If Rafin's relatives lived in his village, then the fuming would be distinct from the killing of them in their sleep.