The Collaborative International Dictionary of English v.0.48:

Pickup \Pick"up\, or Pick-up \Pick"-up`\, n. [Colloq., Cant, or
   Slang]
   1. Act of picking up, as, in various games, the fielding or
      hitting of a ball just after it strikes the ground.
      [Webster 1913 Suppl.]

   2. That which picks up; specif.: (Elec.) same as Brush b.
      [Webster 1913 Suppl.]

   3. One that is picked up, as a meal hastily got up for the
      occasion, a chance acquaintance, an informal game, etc.
      [Webster 1913 Suppl.]

   4. a social companion for the evening who is met without
      prior arrangement, as at a singles bar; also, the act of
      joining with such a companion in that fashion.
      [PJC]

   5. (Automobiles) acceleration; a measure of the ability of a
      vehicle to accelerate.
      [PJC]

   6. (Electronics) a component of a phonograph which contains
      the stylus and also components for converting the
      vibrations of the stylus into electrical impulses for
      subsequent processing into sound; often referred to as a
      cartridge; also, the process of converting vibrations
      into electrical impulses.
      [PJC]

   7. (Electronics) the conversion of sound or light into
      electrical signals in a sound or image recording or
      transmitting device.
      [PJC]

   8. (Vehicles) a small truck having an enclosed driver's
      compartment (cab) but an open rear with usually low sides
      and a tailgate. Also called pickup truck.
      [PJC]

   9. a hitchhiker who has been picked up.
      [PJC]

WordNet (r) 3.0 (2006):

pickup
    n 1: a light truck with an open body and low sides and a
         tailboard [syn: pickup, pickup truck]
    2: a warrant to take someone into custody; "put out a pickup on
       that man"
    3: anything with restorative powers; "she needed the pickup that
       coffee always gave her" [syn: pickup, pick-me-up]
    4: a casual acquaintance; often made in hope of sexual
       relationships
    5: the attribute of being capable of rapid acceleration; "his
       car has a lot of pickup" [syn: pickup, getaway]
    6: mechanical device consisting of a light balanced arm that
       carries the cartridge [syn: tone arm, pickup, pickup
       arm]
    7: an electro-acoustic transducer that is the part of the arm of
       a record player that holds the needle and that is removable
       [syn: cartridge, pickup]
    8: the act or process of picking up or collecting from various
       places; "garbage pickup is on Mondays and Thursdays"
    9: the act of taking aboard passengers or freight

Moby Thesaurus II by Grady Ward, 1.0:

192 Moby Thesaurus words for "pickup":
   Gramophone, Great Leap Forward, Jezebel, PA, PA system,
   Sunday drive, Victrola, accelerando, acceleration, acquaintance,
   advance, advancement, advocate, aggravation, airing, alter ego,
   amelioration, amendment, apprehension, arrestation, arrestment,
   ascent, audio sound system, audiophile, backer, bad woman, baggage,
   beefing-up, best friend, bettering, betterment, binaural system,
   bitch, bitch box, blowing up, blowup, booking, boost, bosom friend,
   bracer, broad, brother, bullhorn, cartridge, casual acquaintance,
   ceramic pickup, changer, chippy, clitoromaniac, close acquaintance,
   close friend, cocotte, concentration, condensation, confidant,
   confidante, consolidation, crystal pickup, deepening,
   derived four-channel system, detention,
   discrete four-channel system, drab, drive, easy lay, easy woman,
   enhancement, enrichment, eugenics, euthenics, exacerbation,
   exaggeration, explosion, familiar, favorer, fellow,
   fellow creature, fellowman, floozy, four-channel stereo system,
   frail sister, friend, furtherance, getaway, grisette, harridan,
   headway, heating-up, heightening, hi-fi, hi-fi fan, high-fidelity,
   hussy, hysteromaniac, impetus, improvement, information explosion,
   inseparable friend, intensification, intercom,
   intercommunication system, intimate, jade, joyride, jukebox, lift,
   loose woman, lover, magnetic pickup, magnification, melioration,
   mend, mending, mobile camera, monaural system, mono, nab, needle,
   neighbor, nickelodeon, nymphet, nympho, nymphomaniac, other self,
   outside pickup, partisan, phonograph, photoelectric pickup,
   pick-me-up, pinch, population explosion, preferment, progress,
   progression, promotion, public-address system,
   quadraphonic sound system, quean, quickening,
   radio-phonograph combination, record changer, record player,
   recovery, redoubling, refresher, reinforcement, remote pickup,
   repository, restoration, revival, reviver, ride, rise, slut,
   sound reproduction system, sound truck, speedup, spin, spot pickup,
   squawk box, step-up, stereo, strengthening, strumpet, stylus,
   supporter, sympathizer, system, tape deck, tape recorder, tart,
   telecamera, television camera, thrust, tightening, tone arm,
   transcription turntable, trollop, trull, turntable, upbeat, uplift,
   upping, upswing, uptrend, upward mobility, uteromaniac, wanton,
   well-wisher, wench, whirl, whore