"Come on, let’s get destroying... Confringo? Stupefy? Bombarda? Which would you use?"
-- Albus Potter to Delphi (CC3.16)
Bombarda is the incantation for a rather loud spell for destruction.
References from the canon
Bombarda was suggested to Scorpius Malfoy by Albus Potter as a way to destroy the Experimental Time-Turner, although Scorpius feared it would "wake up everyone in Hogwarts" (CC3.16).
From French bombarde = to catapult large stones at a target
This spell had only appeared previously in the Harry Potter films and was not created by Rowling. Since the script for Cursed Child was also not written by Rowling, the canonicity of Bombarda is rather questionable by the Lexicon's stringent definition of that term. However, if we exclude Bombarda for that reason, we'd have to exclude pretty much all of Cursed Child -- and Rowling clearly considers that play to be canon. So we're stuck with it. -- SVA
From the Web
"Bombarda" from Harry Potter Wiki