Source : Webster's Revised Unabridged Dictionary (1913)

Afire \A*fire"\, adv. & a. [Pref. a- + fire.]
   On fire.

Source : WordNet®

afire
     adj : lighted up by or as by fire or flame; "forests set ablaze
           (or afire) by lightning"; "even the car's tires were
           aflame"; "a night aflare with fireworks"; "candles
           alight on the tables"; "blazing logs in the fireplace";
           "a burning cigarette"; "a flaming crackling fire";
           "houses on fire" [syn: {ablaze(p)}, {afire(p)}, {aflame(p)},
            {aflare(p)}, {alight(p)}, {blazing}, {burning}, {flaming},
            {on fire(p)}]