Ambassador class heavy cruiser.
Heavy cruiser Constitution
In starship classification, a heavy cruiser is a large multi-purpose starship, a term sometimes used synonymously with battle cruiser. While the Federation considered their Template:ShipClass 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)
Template:ShipClass starships were also considered heavy cruisers in their heyday. (TNG: "Conspiracy") In an alternate timeline, the Ambassador-class was simply referred to as a cruiser. (TNG: "Yesterday's Enterprise")
Background
The term "heavy cruiser" has been used only twice throughout all of Star Trek, where it was spoken in reference to the Ambassador-class ship, and on an on-screen display of the Constitution-class. All other references to large ships have used the term "battle cruiser".
The term heavy cruiser first came into use in the Star Fleet Technical Manual. It was used in the script description of the Klingon Template:ShipClass ships in Star Trek: The Motion Picture, and was thereafter picked up by the production staff on TNG in their behind-the-scenes technical texts (such as the Deep Space Nine Technical Manual). Remnants of the original usage can be seen in background graphics on the bridge in Star Trek III.
In addition to the above, the following classes were referred to as "heavy cruisers" exclusively in the Star Trek: Deep Space Nine Technical Manual:
- Template:ShipClass
- Template:ShipClass
- Jem'Hadar battle cruiser
- Template:ShipClass
- Template:ShipClass
Rick Sternbach in an interview with Star Trek: The Magazine, stated that the Template:ShipClass was designated a heavy cruiser.