"metallic iron disulfide," occurring naturally in cubes and crystals, "fool's gold," 1550s, from Old French pyrite (12c.), from Latin pyrites, from Greek pyritēs lithos "stone of fire, flint" (so called because it glitters), from pyritēs "of or in fire," from pyr (genitive pyros) "fire" (from PIE root *paewr- "fire"). Related: Pyritic.

also hell-fire, "the fire of Hell, eternal torment," from Old English hellefyr, in which helle is the genitive case of hell. It translates Greek gehenna tou pyros, literally "hell of fire." Also used in Middle English for "erysipelas" (mid-15c.).

also fire-man, late 14c., "tender of a fire," from fire (n.) + man (n.). From 1650s as "furnace-tender" of a early steam engine. As "person hired to put out (rather than tend) fires" it is attested from 1714. For "stoker," Old English had fyrbeta.

*āter-, Proto-Indo-European root meaning "fire." It forms all or part of: atrabiliary; atrabilious; atrium; atrocious.

It is the hypothetical source of/evidence for its existence is provided by: Old Persian atar "fire;" Latin ater "black" ("blackened by fire"), atrox "frightful" ("of fiery or threatening appearance").

"vomiting fire," c. 1600, from Late Latin ignivomous, from Latin ignis "fire" (see igneous) + vomere "to vomit" (see vomit (n.)).

"empyreal," mid-14c. (as empyre), probably via Medieval Latin empyreus, from Greek empyros "fiery," from assimilated form of en (see en- (2)) + pyr "fire" (from PIE root *paewr- "fire"). As an adjective in English from early 15c. The etymological sense is "formed of pure fire or light." In ancient Greek cosmology, the highest heaven, the sphere of pure fire; later baptized with a Christian sense of "abode of God and the angels."

also re-ignite, "catch fire again; cause to catch fire again," 1823, from re- "again" + ignite. Related: Reignited; reigniting; reignition.

also fire-storm, 1580s, in poetry, from fire (n.) + storm (n.). From 1945 in reality, in reference to nuclear war.

also fire-side, 1560s, from fire (n.) + side (n.). Symbolic of home life by 1848. As an adjective from 1740s; especially suggesting the intimately domestic.

1540s, "action of applying fire or setting on fire," verbal noun from fire (v.). From c. 1600 as "act of discharging firearms." Firing squad is attested from 1891 in reference to military executions; earlier as "those selected to fire over the grave of anyone interred with military honors" (1864); earlier in both senses is firing-party (1798 in reference to military executions; 1776 in reference to military funerals).