blast
bomb
The word 'boom' can be used as a word for explosion that starts with a b.
Synonyms of 'Explosion' which begin with the letter 'B' include; blast, burst, blow up, blow out, bang and bark.
blast
bomb
Brachiosaurus is a dinosaur. It begins with the letter B.
Boston
Bob, Brianna.
Begonia
brenda
A bombing?
Bewitched