The Collaborative International Dictionary of English v.0.48:

Deflagrate \Def"la*grate\, v. i. [imp. & p. p. Deflagrated; p.
   pr. & vb. n. Deflagrating.] [L. deflagratus, p. p. of
   deflagrare to burn up; de- + flagrare to flame, burn.]
   (Chem.)
   To burn with a sudden and sparkling combustion, as niter;
   also, to snap and crackle with slight explosions when heated,
   as salt.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Deflagrate \Def"la*grate\, v. t. (Chem.)
   To cause to burn with sudden and sparkling combustion, as by
   the action of intense heat; to burn or vaporize suddenly; as,
   to deflagrate refractory metals in the oxyhydrogen flame.
   [1913 Webster]

WordNet (r) 3.0 (2006):

deflagrate
    v 1: cause to burn rapidly and with great intensity; "care must
         be exercised when this substance is to be deflagrated"
    2: burn with great heat and intense light; "the powder
       deflagrated"