To attack with bombs or heavy artillery, or to overwhelm someone with questions, criticism, or lots of information.
From Medieval Latin 'bombarda' (a type of cannon), possibly from Latin 'bombus' (a loud sound). The word originally meant a specific medieval weapon before generalizing to mean attacking with heavy fire.
The word 'bombard' traveled from the sound it made ('bombus') to the weapon that made the sound, then to any violent attack, and finally to non-violent overwhelming—words evolve when metaphors become normal.
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