flōˈjistən noun
( -s )
Etymology: New Latin, from Greek, neuter of phlogistos burnt, inflammable, from phlogizein to set on fire, from phlog-, phlox flame, from phlegein to burn — more at black
: the hypothetical principle of fire or inflammability regarded by the early chemists as a material substance
metals were supposed to be prepared from their calxes by the union of the latter with phlogiston — M.C.Sneed & J.L.Maynard
what manner of substance or principle could phlogiston be that when it was added to another material the total mass or weight diminished? — J.B.Conant