"Strike cruiser" is a term used by the Klingon Defense Force (among others) for some mid-range starships, smaller and less versatile than mainline capital ships, but more able to act as a cruiser in combat situations when compared to than mere scouting or patrol ships. They tend to be most effective when operating in groups or supporting larger vessels. The equivalent terms used by the Federation Starfleet would probably be "light cruiser" or "destroyer".