What is Broadside?

Legal Definition
A broadside is the side of a ship, the battery of cannon on one side of a warship; or their coordinated fire in naval warfare. From the 16th century until the early decades of the steamship, vessels had rows of guns set in each side of the hull. Firing all guns on one side of the ship became known as a "broadside". The cannons of 18th century men of war were accurate only at short range, and their penetrating power mediocre, entailing that the thick hulls of wooden ships could only be pierced at short ranges. These wooden ships sailed closer and closer towards each other until cannon fire would be effective. Each tried to be the first to fire a broadside, often giving one party a decisive headstart in the battle when it crippled the other ship.
-- Wikipedia
Legal Definition
With the side turned to a particular thing or on the side.