The Collaborative International Dictionary of English v.0.48:

Cruiser \Cruis"er\ (kr?"z?r), n.
   One who, or a vessel that, cruises; Specif.: (Nav.) A
   man-of-war less heavily armed and armored than a battle ship,
   having great speed, and generally of from two thousand to
   twelve thousand tons displacement.
   [1913 Webster + Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

cruiser
    n 1: a car in which policemen cruise the streets; equipped with
         radiotelephonic communications to headquarters [syn:
         cruiser, police cruiser, patrol car, police car,
         prowl car, squad car]
    2: a large fast warship; smaller than a battleship and larger
       than a destroyer
    3: a large motorboat that has a cabin and plumbing and other
       conveniences necessary for living on board [syn: cabin
       cruiser, cruiser, pleasure boat, pleasure craft]

Moby Thesaurus II by Grady Ward, 1.0:

225 Moby Thesaurus words for "cruiser":
   Black Maria, LC, LSD, LSM, SC, adventurer, aircraft carrier,
   aircraft tender, almadia, alpinist, ammunition ship, ark,
   assault transport, astronaut, auxiliary, barge, battleship,
   bomb ketch, buss, cabin cruiser, camper, canoe, capital ship,
   caravel, cargo boat, carrier, carryall, cat, catamaran, climber,
   coast guard cutter, cockle, cockleshell, cog, comers and goers,
   communications ship, commuter, convoy, coracle, corvette,
   cosmopolite, cutter, depot ship, destroyer, destroyer leader,
   destroyer tender, dinghy, dispatch boat, dreadnought, drifter,
   dugout, eagle boat, escort carrier, escort vessel, excursionist,
   explorer, fare, ferry, ferryboat, fille de joie, fire ship,
   first-rate, fishing boat, flagship, flattop, frigate, fuel ship,
   funny, galley, gig, glider, globe-girdler, globe-trotter, goer,
   gondola, guided missile cruiser, gunboat, hajji, harlot,
   heavy cruiser, hooker, hospital ship, houseboat, hoy, hustler,
   hydrofoil, hydroplane, ironclad, jet set, jet-setter, jolly,
   jolly boat, journeyer, kayak, landing craft, launch, liberty boat,
   lifeboat, light cruiser, lighter, line-of-battle ship, longboat,
   mailer, mariner, mine sweeper, minisub, monitor, mosquito boat,
   motor launch, motorboat, mountaineer, nightwalker, outboard,
   outrigger canoe, paddy wagon, palmer, passenger, passerby,
   pathfinder, patrol boat, patrol car, patrol wagon, picketboat,
   pilgrim, pilot, pilot boat, pinnace, pioneer, piragua, pirogue,
   police van, pontoon, post boat, poule, power cruiser, powerboat,
   pram, privateer, protected cruiser, prowl car, punt, racer,
   racing shell, raider, ram, randan, receiving ship,
   reconnaissance ship, rocket boat, rowboat, rowing boat, rubberneck,
   rubbernecker, runabout, sailor, sampan, scooter, scout,
   scout cruiser, scow, scull, seaplane carrier, sedan cruiser,
   shallop, shell, ship of war, shipplane carrier, showboat,
   sightseer, skiff, small boat, sneakbox, speedboat, spy ship,
   squad car, steam launch, storeship, storm boat, straphanger,
   streetwalker, submarine, submarine chaser, submarine patrol boat,
   submarine tender, submersible, superdreadnought, surfboat, sweeper,
   tanker, tender, tomato, tourer, tourist, towboat, trailblazer,
   trailbreaker, transient, transport, traveler, trawlboat, trawler,
   trekker, trimaran, tripper, troopship, trow, tug, tugboat,
   turret ship, viator, visiting fireman, voortrekker, voyager,
   voyageur, wagon, wanigan, warship, wayfarer, whale-gig, whaleboat,
   wherry, whore, world-traveler, yawl, yawl boat