I know that the term had a special meaning in TOS, but never defined. I rewatched Relics today and Scotty says he served aboard many vessels: freighters, cruisers, starships... I read Timo's guide to starships a while back, and Timo thinks that they are something akin to Capital ships (correct me if I'm wrong Timo, I don't have the link handy, I might have read it somewhere else). I have a bit of problem with this, because capital ships were battleships and battlecruisers, and they were marked as such so that enemy nations could quickly assess strength of each nation, and so that they could keep to the treaty limits. Again, correct me if I'm wrong, I'm not good with that time period. The problem with this in Star Trek is obvious: You can't measure the strength of Federation or Klingons by looking at how many capital ships they have, it's useless. In Star Trek, small ships fight and are crucial to battles as seen in DS9. If Romulans judged the strength of Starfleet by the numbers of Galaxy and Nebula class ships compared to their own Warbirds, they would be in trouble (if indeed those are considered capital ships - Yamato's captain calls them cruisers). So what are they? Are they simply multi-role ships that can execute any mission given to it? Are they "capital ships" with a different meaning than the original meaning? A slightly different defintion perhaps?