The term 'broadside' DOES apply to carriers. This is a fairly ancient term (well, probably around 15th century), which has NO such limitations, because it was NOT conceived as something that would refer to a particular type of ship. Naturally, nobody ever used it in reference to a real carrier, since real carriers a) have no weapons, and b) do not engage in naval combat. WC carriers are different. They have guns, and they frequently are seen fighting against other capital ships. Indeed, we see in the WC Movie a carrier engaging an enemy ship, and... "Give them a broadside, Mr. Gerard!"