1660s (trans.), "kindle or set on fire, cause to burn," from Latin ignitus, past participle of ignire "set on fire, make red hot," from ignis "fire" (see igneous). Attested earlier as an adjective (1550s). Intransitive sense of "catch fire, begin to burn" is from 1818. Related: Ignited; igniting.
late 14c., bonfir, banefire, "a fire in which bones are burned;" see bone (n.) + fire (n.). The original specific sense became obsolete and was forgotten by 18c. The general sense of "large open-air fire from any material for public amusement or celebration" is by mid-16c. and that of "large fire for any purpose" from 17c.
"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.).