WordWeb Online

1. Streaming, flapping or spreading wide as if in a current of air
   "flags aflare in the breeze";
   - flaring
    
2. Flaming as it burns
   "forests set aflare by lightning"; "a night aflare with fireworks";
   - ablaze, afire [literary], aflame, alight, on fire, burning, in flames

See also: lighted, lit, moving