Yep...
Still, the Iceni is called a Frigate; I simply classified it a bit more specifically; an attack frigate. It's faster and has weaponry concentrated toward a single area (one side).
The Iceni as a Dreadnought is very far fetched; other then the amount of armour it has, it shares nearly nothing in common with a destroyer. It is over twice as fast (35m/s iirc) and is a fraction the size (800m iirc). It's definately not a dreadnought by your definition.
I'll personally be using the Monitor.
It's
Dreadnought.
Dreadnought was simply a modernized battleship - instead of variable armament it had the same-caliber main batteries ("all big gun"), making it far more efficient than previous battleship models which sported many different calibers and gun types. The thing about Dreadnought is that it made all other battleship classes pretty obsolete overnight. After HMS Dreadnought was introduced in 1905 all battleship construction switched to ships of similar type. Iowas, Yamatos and so on are actually dreadnoughts, but nowadays the term is interchangable with the term "battleship". HMS Dreadnought was also fast and well-armoured, as well as being bigger and far more modern vessel than previous battleship types.
In science fiction, however, dreadnought is pretty commonly used to describe a certain type of vessel, a really big battleship which does not usually house a fighter bay.
A compact warship with less tonnage than a battleship but which is far more potent than a cruiser is a battlecruiser. They are described as either "upscaled cruisers" or "downscaled BBs", whatever suits you.
Of course, none of these traditions really mean jack **** when you can make up your own rules and pull history out of your ass, and in FS universe the entire naming convention is a huge mess anyways..