The Collaborative International Dictionary of English v.0.48:

Booster \Boost"er\ (b[=oo]st"[~e]r), n.
   1. (Elec.) An instrument for regulating the electro-motive
      force in an alternating-current circuit; -- so called
      because used to "boost", or raise, the pressure in the
      circuit.
      [Webster 1913 Suppl.]

   2. an enthusiastic supporter.
      [PJC]

   3. the first stage of a multistage rocket, providing all or
      part of the driving force at lift-off and until the second
      stage ignites, whether or not the booster stage is
      detached after the fuel is spent. Also called booster
      rocket. In some cases, a booster has been used to assist
      the takeoff of airplanes.
      [PJC]

   4. (Med.) an immunizing medication given after an initial
      immunizing treatment, to provide increased or extended
      immunity. Also called booster dose. When in the form of
      an injection, it may be called a booster shot.
      [PJC]

   5. any auxiliary device or part of a device to provide
      increased power, force, or effectiveness, as with a
      pumping device.
      [PJC]

   6. (Mil.) an explosive charge which is more powerful than a
      primer, used in conjunction with a primer to assure
      detonation of the main charge. Integrated blasting caps
      containing separate compartments for primer and booster
      are used as detonators for certain explosives.
      [PJC]

WordNet (r) 3.0 (2006):

booster
    n 1: a person who backs a politician or a team etc.; "all their
         supporters came out for the game"; "they are friends of the
         library" [syn: supporter, protagonist, champion,
         admirer, booster, friend]
    2: someone who is an active supporter and advocate [syn:
       promoter, booster, plugger]
    3: a thief who steals goods that are in a store [syn: booster,
       shoplifter, lifter]
    4: an amplifier for restoring the strength of a transmitted
       signal [syn: booster, booster amplifier, booster
       station, relay link, relay station, relay transmitter]
    5: the first stage of a multistage rocket [syn: booster,
       booster rocket, booster unit, takeoff booster, takeoff
       rocket]
    6: an additional dose that makes sure the first dose was
       effective [syn: booster, booster dose, booster shot,
       recall dose]

Moby Thesaurus II by Grady Ward, 1.0:

112 Moby Thesaurus words for "booster":
   Comsat, Intelsat, Syncom, Telstar, adherent, admirer, amateur,
   antitoxin, applauder, appreciator, bag, bang, blind, body snatcher,
   bonnet, booster amplifiers, booster dose, booster rocket,
   booster shot, boosters, buff, capper, chicken thief, claqueur,
   collector, commender, communication satellite, con man, crook,
   deck, den of thieves, devotee, dilettante, dose, draft, dropping,
   drug packet, embezzler, encomiast, eulogist, eulogizer, extoller,
   fan, fancier, filcher, fix, follower, ganef, ghoul, grafter,
   grave robber, groupie, hit, hypodermic, hypodermic injection,
   idolater, idolizer, injection, inoculation, jet injection,
   jewel thief, land pirate, land shark, land-grabber, larcener,
   larcenist, lauder, lifter, mainlining, multistage rocket,
   narcotic injection, narcotic shot, overdose, panegyrist, peculator,
   petty thief, pilferer, plugger, poacher, popping, portion, potion,
   praiser, promoter, prowler, puffer, purloiner, relay links, robber,
   rooter, scrounger, shill, shooting up, shoplifter, shot,
   single-stage rocket, skin-popping, sneak thief, stealer,
   step rocket, stick, stratovision, swindler, thief,
   three-stage rocket, tout, touter, vaccination, vaccine, votary,
   white-collar thief, worshiper



The Free On-line Dictionary of Computing (30 December 2018):

Booster

   A data-parallel language.

   "The Booster Language", E. Paalvast, TR PL 89-ITI-B-18, Inst
   voor Toegepaste Informatica TNO, Delft, 1989.