phlo·gis·ton (flō-jĭstŏn′, -tən)
A hypothetical substance formerly thought to be a volatile constituent of all combustible substances, released as flame in combustion.
[From Greek, neuter of phlogistos, inflammable, from phlogizein, to set on fire, from phlox, phlog-, flame; see bhel-1 in the Appendix of Indo-European roots.]
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