phlogiston
Concise Oxford English Dictionary © 2008 Oxford University Press:
phlogiston /fləˈdʒɪst(ə)n, -ˈgɪst-/
▶noun a substance supposed by 18th-century chemists to exist in all combustible bodies, and to be released in combustion.
– origin C18: mod. L., from Gk phlogizein ‘set on fire’.
'phlogiston' also found in these Oxford entries:

