The Collaborative International Dictionary of English v.0.48:

Generator \Gen"er*a`tor\, n. [L.]
   1. One who, or that which, generates, begets, causes, or
      produces.
      [1913 Webster]

   2. An apparatus in which vapor or gas is formed from a liquid
      or solid by means of heat or chemical process, as a steam
      boiler, gas retort, or vessel for generating carbonic acid
      gas, etc.
      [1913 Webster]

   3. (Mus.) The principal sound or sounds by which others are
      produced; the fundamental note or root of the common
      chord; -- called also generating tone.
      [1913 Webster]

   4. (Elec.) Any machine that transforms mechanical into
      electrical energy; a dynamo.
      [Webster 1913 Suppl.]

   5. (Math.) a mathematical entity which, when subjected to an
      operation, yields another mathematical entity; also, a
      generatrix.
      [PJC]

WordNet (r) 3.0 (2006):

generator
    n 1: an apparatus that produces a vapor or gas
    2: engine that converts mechanical energy into electrical energy
       by electromagnetic induction
    3: someone who originates or causes or initiates something; "he
       was the generator of several complaints" [syn: generator,
       source, author]
    4: an electronic device for producing a signal voltage

Moby Thesaurus II by Grady Ward, 1.0:

300 Moby Thesaurus words for "generator":
   AC motor, Corliss engine, Otto engine, PCV valve, Wankel engine,
   accelerator, actuator, aeromotor, agent, air engine, alternator,
   ammeter, amplifier, ancestors, anode, apprentice, architect,
   armature, artificer, artist, attenuator, audio-frequency tube,
   author, autoconverter, autostarter, autotransformer,
   ballast regulator, ballast tube, battery charger, beam engine,
   beam-switching tube, bearings, begetter, beginner, blowing engine,
   bonnet, boot, brake, brush, bucket seat, builder, bumper,
   cam engine, camshaft, cap, capacitator, capacitor, capacitor motor,
   carburetor, catalyst, cathode, causer, charger, chassis, choke,
   choking coil, clock, clutch, coil, commutator, commutator motor,
   compensated motor, compensator, compound motor, conceiver,
   condenser, condensing engine, connecting rod, constructor,
   control relay, control resistor, controller, converter,
   convertible top, convertor, coupling, cowl, craftsman, crank,
   crankcase, crankshaft, creator, current regulator, cutout,
   cylinder, cylinder head, damper, dash, dashboard, designer,
   detector, deviser, diagonal engine, differential,
   direct-acting engine, discoverer, discriminator, distributor,
   donkey engine, doubler, dynamo, dynamotor, effector,
   electric motor, electrode, electrophorus, electroscope, engenderer,
   engineer, executor, executrix, exhaust, exhaust pipe, fan, father,
   feedback amplifier, fender, fire engine, flywheel, focus tube,
   founder, fuse, galvanic pile, galvanoscope, gas turbine engine,
   gear, gearbox, gearshift, grid, ground, grower, headlight,
   headrest, hood, horn, hot-air engine, hydraulic engine, hydro-jet,
   iconoscope, ignition, impulse duct engine, inaugurator, inductor,
   industrialist, initiator, inspirer, instigator, institutor,
   insulator, intake, interrupter, introducer, inventor,
   inverted engine, inverter, ion engine, ion rocket, jet, journeyman,
   jumper, lightning rod, limiter, local-oscillator tube, magnet,
   magnetic relay, magneto, magnetoscope, maker, manifold,
   manufacturer, master, master craftsman, meter relay, mixer tube,
   modulator, mother, motor-generator, mover, muffler, multiplier,
   multipurpose tube, multivibrator, organizer, originator,
   oscillator, oscilloscope, outboard motor, outlet, output tube,
   pancake engine, parent, parking light, past master, patriarch,
   phase inverter, picture tube, pile, piston, piston engine,
   piston-valve engine, planner, plasma engine, plug, pocket, points,
   portable engine, power brakes, power steering, power tube,
   precursor, pressure transducer, prime mover, primum mobile,
   producer, pulse generator, pulse-jet engine, pumping engine,
   push button, radial engine, radiator, radio-frequency tube, raiser,
   ramjet, ramjet engine, reactor, realizer, rear-view mirror,
   receiving tube, receptacle, reciprocating engine, rectifier,
   rectifier tube, refrigerating engine, regenerator, regulator,
   relay, reluctance amplifier, repeater, resistance box, resistor,
   resojet engine, rheostat, rocket engine, rocket motor,
   rotary engine, rotary-piston engine, rotor motor, seat belt,
   self-starter, selsyn, servo amplifier, servomotor, shaper,
   shock absorber, shunt, shunt motor, sire, smith, socket,
   spark coil, spark plug, speedometer, springs, starter,
   steam engine, steering wheel, step-down transformer,
   supercharged engine, switch, synchronous converter,
   synchronous motor, tap, terminal, thermal timing relay,
   three-phase motor, time switch, timer, toggle switch, top,
   traction engine, transducer, transformer, transmission,
   transmitter, trickle charger, trigger tube, turbine, turbojet,
   turbojet engine, universal, valve, variable-speed motor,
   vernier engine, vertical engine, voltage changer,
   voltage regulator, voltage transformer, windscreen, windshield,
   wright