Source : Webster's Revised Unabridged Dictionary (1913)

Combust \Com*bust"\, a. [L. combustus, p. p. of comburere to
   burn up; com- + burere (only in comp.), of uncertain origin;
   cf. bustum fineral pyre, prurire to itch, pruna a live coal,
   Gr. pyrso`s firebrand, Skr. plush to burn.]
   1. Burnt; consumed. [Obs.] --Chaucer.

   2. (Astron.) So near the sun as to be obscured or eclipsed by
      his light, as the moon or planets when not more than eight
      degrees and a half from the sun. [Obs.]

            Planets that are oft combust.         --Milton.

Source : WordNet®

combust
     v 1: cause to burn or combust; "The sun burned off the fog"; "We
          combust coal and other fossil fuels" [syn: {burn}]
     2: start to burn or burst into flames; "Marsh gases ignited
        suddenly"; "The oily rags combusted spontaneously" [syn: {erupt},
         {ignite}, {catch fire}, {take fire}, {conflagrate}]
     3: get very angry and fly into a rage; "The professor combusted
        when the student didn't know the answer to a very
        elementary question"; "Spam makes me go ballistic" [syn: {flip
        one's lid}, {blow up}, {throw a fit}, {hit the roof}, {hit
        the ceiling}, {have kittens}, {have a fit}, {blow one's
        stack}, {fly off the handle}, {flip one's wig}, {lose
        one's temper}, {blow a fuse}, {go ballistic}]
     4: cause to become violent or angry; "Riots combusted Pakistan
        after the U.S. air attacks on Afghanistan"
     5: undergo combustion; "Maple wood burns well" [syn: {burn}]