(n.) A man-of-war less heavily armed and armored than a battle ship, having great speed, and generally of from two thousand to twelve thousand tons displacement.
(n.) One who, or a vessel that, cruises; - usually an armed vessel.
Webster's Dictionary - Armored Cruiser
A man-of-war carrying a large coal supply, and more or less protected from the enemy's shot by iron or steel armor. There is no distinct and accepted classification distinguishing armored and protected cruisers from each other, except that the first have more or heavier armor than the second.