We need to speculate first on whether the ship was the first of her kind.
I mean, she probably was not the only one of her kind. Why would Marcus choose to go to war before the completion of a mighty warfleet? The construction project existed, and not in great secrecy, either, even if Kirk was not told (desktop models and all). And Marcus was ready to throw away the Fleet's newest flagship, suggesting these as such big ships were immaterial to his ultimate (and immediate) war designs.
So, was the Vengeance, apparently still unfinished, perhaps the fifth dreadnought in the Fleet? And was her name thus just the fifth in a series, with four more "sensible" names preceding hers, perhaps in a classic warship theme of "alliterative qualities"? Vigilance, Vindictive, Vanquisher, Volunteer, Vengeance...?
Or are we dealing with the Vengeance class of dreadnoughts here? Or even the Dreadnought class of medium cruisers or whatnot?
Timo Saloniemi