fire (n.) Look up fire at Dictionary.com
Old English fyr, from Proto-Germanic *fuir (cognates: Old Saxon and Old Frisian fiur, Old Norse fürr, Middle Dutch and Dutch vuur, Old High German fiur, German Feuer), from PIE *perjos, from root *paewr- (cognates: Armenian hur "fire, torch," Czech pyr "hot ashes," Greek pyr, Umbrian pir, Sanskrit pu, Hittite pahhur "fire").

Current spelling is attested as early as 1200, but did not fully displace Middle English fier (preserved in fiery) until c.1600.

PIE apparently had two roots for fire: *paewr- and *egni- (source of Latin ignis). The former was "inanimate," referring to fire as a substance, and the latter was "animate," referring to it as a living force (see water (n.1)).

Fire applied in English to passions, feelings, from mid-14c. Meaning "action of guns, etc." is from 1580s. Firecracker is American English coinage for what is in England just cracker, but the U.S. word distinguishes it from the word meaning "biscuit." Fire-engine attested from 1680s. The figurative expression play with fire "risk disaster" is from 1887; phrase where's the fire? "what's the hurry?" first recorded 1924.
fire (v.) Look up fire at Dictionary.com
c.1200, furen, figurative, "arouse, excite;" literal sense of "set fire to" is from late 14c., from fire (n.). The Old English verb fyrian "to supply with fire" apparently did not survive into Middle English.

The sense of "sack, dismiss" is first recorded 1885 in American English (earlier "throw (someone) out" of some place, 1871), probably from a play on the two meanings of discharge: "to dismiss from a position," and "to fire a gun," fire in the second sense being from "set fire to gunpowder," attested from 1520s. Of bricks, pottery, etc., from 1660s. Related: Fired; firing. Fired up "angry" is from 1824. Firing squad is attested from 1904.