(covers information from several alternate timelines)
In starship classification, a heavy cruiser was a large multi-purpose starship, a term sometimes used synonymously with battle cruiser. While the Federation considered their Constitution-class starships to be heavy cruisers in their heyday, the Klingons referred to the same vessel, in their terms, as a battle cruiser. (Star Trek III: The Search for Spock)
|attack cruiser • attack fighter • battle cruiser • battleship • bird-of-prey • cruiser • destroyer • dreadnought • escort vessel • explorer ship • flagship • freighter • frigate • garbage scow • heavy cruiser • hospital ship • interceptor • light cruiser • luxury liner • patrol ship • prison ship • raider • runabout • science vessel • scout ship • star cruiser • starliner • supply ship • survey ship • tanker • timeship • training vessel • transport ship • tug • warbird • warship|
The term "heavy cruiser" was first used in the shooting script for Star Trek: The Motion Picture for describing the Klingon K't'inga-class starships. It was used later for an on-screen display of the Constitution-class, which was from the Star Fleet Technical Manual, and and it was spoken in reference to the Ambassador-class. It was thereafter picked up by the production staff on Star Trek: The Next Generation and Star Trek: Deep Space Nine in their behind-the-scenes technical texts (such as the Star Trek: Deep Space Nine Technical Manual).
In addition to the above, the following classes were referred to as "heavy cruisers" exclusively in the Star Trek: Deep Space Nine Technical Manual: