The term 'BOOM ALTERNATIVE' can be broken down into four crossword solutions: BUST (4 letters), KABLOOEY (8 letters), BANG (4 letters), and RAH (3 letters). BUST is a slang term for an explosion, usually referring to a loud noise. KABLOOEY is an onomatopoeia for a loud explosion, often used in comic books. BANG is another onomatopoeia for a loud noise, usually associated with a gunshot. Finally, RAH is an exclamation of joy or triumph, usually shouted in celebration. All of these words are alternatives to the word 'BOOM, ' which is also an onomatopoeia for a loud noise.