(1):

(n.) A sound produced by an explosive impulse of the breath; (Phonetics) one of consonants p, b, t, d, k, g, which are sounded with a sort of explosive power of voice. [See Guide to Pronunciation, ? 155-7, 184.]

(2):

(n.) An explosive agent; a compound or mixture susceptible of a rapid chemical reaction, as gunpowder, or nitro-glycerine.

(3):

(a.) Driving or bursting out with violence and noise; causing explosion; as, the explosive force of gunpowder.