Gents, the term "Battlecruiser" was employed strictly to replace the term "Dreadnaught" when that term fell out of favor.
A Dreadnaught was the precursor to the true Battleship, starting with the HMS Dreadnaught that started it all. The ship was larger and more heavily armed than a Heavy Cruiser.
When true Battleships entered service, "Dreadnaught" was replaced by "Battlecruiser" and describes a ship that is larger, more heavily armed and armored than a Heavy Cruiser, but less so than a Battleship. Currently, the only active Battlecruiser is the Kirov Class operated by the Russian Navy, Northern Fleet. That is, if they can even afford to operate at all. Those Battlecruisers that were less armored than Heavy Cruisers were so because they were originally old Dreadnaughts, like the HMS Hood, and were no longer up to the armor standards being employed by more advanced Heavy Cruisers.
In most Sci-Fi works that include warships, a Dreadnaught describes a massive ship that fullfills both the role of Battleship and Carrier.
I use this, skipping the small craft:
CR: Corvette. Corvette's have always been small and speedy patrol vessels larger than PT Boats, but smaller than Frigates. They are primarily used by the Italian, Argentinian, Norweigian, French navies to patrol coast lines, hunt subsmarines, provide AAA support to larger ships, or in a pinch attack larger vessels. The US and Royal Navies refer to this class of ship as a Cutter. I feel that the ship higlighted in this thread is a good example of a Corvette. The Shivan Vindhychal is another good example, IMO
FG: Frigate. Frigates are small vessels smaller and more agile than Destroyers. They are primarily used to hunt subs and provide AAA support to a Battle Group. They also make excellant escorts, and shipping lane control craft. I added two turrets to a Satis once to make a Frigate. A good example. I also think that Aldo's Piranah and Njord are good examples of Frigates, despite being a little large for the class.
DD: Destroyer. Destroyers were first dreamed up to take advantage of new torpedo technology after Naval treaties limited tjhe number of Battleships and Battle and Heavy Cruisers that a nation could possess. All naval thinking at the time revolved around what was called "The Grand Battle" where it was thought that two massive opposing fleets would meet and slug it out with guns. This is before the airplane and the Carrier figured prominently in their thinking. The treaty did not limit the number of smaller vessels a nation could have since it was thought that such small vessels would have no or little value in "The Grand Battle". Nations used the new torpedo technology mounted on smaller vessels to exploit this loophole. A torpedo cares not the size or grandeur of a ship, and made great Battleship killers. They small vessels were thus originally called "Battleship-Destroyers" but the name was later shortened to just Destroyer. This meaning have generally been lost to time, however, as the Destroyer's role has changed immensely. They now act as escorts, ASW and AA vessels, but can still attack larger ships with missiles and torpedos. The name now describes a class of small multi-task vessels and for that reason I see no logic in calling an Orion or Hectate a Destroyer just because it was allegedly designed to take out Cruisers. The Fenris is a perfect example of a Destroyer, especially if you arm its main turret with torpedos.
Slightly larger and more powerful vessels called Destroyer Leaders or Heavy Destroyers were also designed. You *could* conceivably refer to the Aeolus or Leviathan as such, altough I personally prefer to lump them in the next class. The Cain and the Lilith would fit here too.
CL: Light Cruiser. Pretty self explanatory. Some would say that these are the first class of the "ships of the line", others disagree. In wars past, many of these served support roles like dedicated escort or AAA duty. Some were just enlarged and rearmed Heavy Destroyers, and thus had little armor protection. Still others were designed to fight it out on the line with Heavy Cruisers. I would say that the Mentu, Aeolus, Rakasha, and Leviathan are good examples, but my fav example is Hamano's Ticonderoga.
CLM or CAM: Missile or Torpedo Cruiser: Missile or Guided Missile Cruisers are usually built to provide Air Defense for the fleet, but in most Sci FI circles, are a light or heavy cruiser that is armed with missiles or torpedos instead of guns. Stratcomm has come up with good examples of these IIRC.
CA: Heavy Cruiser. The first true "Ships of the Line" Heavy Cruisers serve only one purpose: To pound opposing vessels into so much scrap. The Deimos and Sobek are perfect examples.
CS: Strike Cruiser. A designation in Sci Fi circles used to describe a heavy cruiser that carries a small number of strike craft like fighters or bombers. The Moloch fits here.
CC: Command Cruiser. Class I added to describe several of the AWACS capable cruisers that the community has come up with.
CB: Battlecruiser. The fall in between the Heavy Cruiser and the Battleship, Battlecruisers were the first battlewagons built. Originally refered to as Dreadnaughts. Soem would say that the Iceni fits here, but I would usually disagree. The Phobos and the Nike fit here very well.
BB: Battleship. We all know what a Battleship is. In the real world BB's carried a couple planes, or none at all. In Sci Fi, they may carry a defense squadron or two, but usually none at all. I would put the Iceni here, as a smaller, fast BB. Anybody remember the PVD Cobra? I would call that a Battleship ( we are re-doing it, btw ). There have been some other good examples around the community too.
CV: Carrier. We all know what a carrier does. Carries strike craft to the battle area and has few anti-ship weapons except those for defense. The designation by the US is CV for fixed wing, or CH for rotary wing carriers. An N is added for nuclear. I have dropped those for obvious reasons. There are lots of different kinds of carriers. Small Carrier Escorts (CVE), whose job is to provide defense squadrons for convoys and larger warships that lack such support of their own (Aldos Gryphon is a good example, I think); Light Carriers (CVL) that are smaller than the larger carriers but provide the same sort of capabilities but on a smaller scale; Strike Carriers (CVS), like the Orion, Typhon, and Demon that provide large numbers of bombers and fighters to any offensive and defensive effort, and can also fight if needed; and the massive Fleet Carriers (CVF), like Aldo's Warlock, that form the nucleus of any Fleet.
DN: Dreadnaught. In contemporary Sci Fi, this describes a massive vessel that performs the duties of both carrier and battleship, although differing definitions exist. Hectate and Ravana are perfect examples.
SD. Super Dreadnaught. We all know what this is. Lucifer and Hades would be good examples.
JN: Juggeranaught. Same as above. Colossus, Sath good examples.
SJ: Super Juggernaught. Describes the massive 10+ kilometer vessels that the community has come up with.
CS: Command Ship. Same as above, but those vessels designed to be flagships more than frontline vessels.
I have also considered a "Planet Killer" class to describe these types of vessels that myself and several others have made.
