phlogiston

UK: /flɒˈdʒɪstɒn/ US: (flō jis′ton, -tən)

WordReference Random House Unabridged Dictionary of American English © 2025

phlo•gis•ton  (flō jis′ton, -tən), n. 

1. Chemistry a nonexistent chemical that, prior to the discovery of oxygen, was thought to be released during combustion.

• Neo-Latin: inflammability, noun, nominal use of Greek phlogistón, neuter of phlogistós inflammable, burnt up; see phlogistic
• 1720–30

Collins Concise English Dictionary © HarperCollins Publishers::

phlogiston / flɒˈdʒɪstɒn -tən/ noun

1. a hypothetical substance formerly thought to be present in all combustible materials and to be released during burning

Etymology: 18th Century: via New Latin from Greek, from phlogizein to set alight; related to phlegein to burn