The Collaborative International Dictionary of English v.0.48:

Transmission \Trans*mis"sion\, n. [L. transmissio; cf. F.
   transmission. See Transmit.]
   1. The act of transmitting, or the state of being
      transmitted; as, the transmission of letters, writings,
      papers, news, and the like, from one country to another;
      the transmission of rights, titles, or privileges, from
      father to son, or from one generation to another.
      [1913 Webster]

   2. (Law) The right possessed by an heir or legatee of
      transmitting to his successor or successors any
      inheritance, legacy, right, or privilege, to which he is
      entitled, even if he should die without enjoying or
      exercising it.
      [1913 Webster]

   3. (Mech.) The mechanism within a vehicle which transmits
      rotational power from the engine to the axle of the wheel
      propelling the vehicle; it includes the gears and
      gear-changing mechanism as well as the propeller shaft.
      [1913 Webster]

   4. The process or event of sending signals by means of a
      radio-frequency wave from an electronic transmitter to a
      receiving device.
      [1913 Webster]

WordNet (r) 3.0 (2006):

transmission
    n 1: the act of sending a message; causing a message to be
         transmitted [syn: transmission, transmittal,
         transmitting]
    2: communication by means of transmitted signals
    3: the fraction of radiant energy that passes through a
       substance [syn: transmittance, transmission]
    4: an incident in which an infectious disease is transmitted
       [syn: infection, contagion, transmission]
    5: the gears that transmit power from an automobile engine via
       the driveshaft to the live axle [syn: transmission,
       transmission system]

Moby Thesaurus II by Grady Ward, 1.0:

177 Moby Thesaurus words for "transmission":
   FCC, FM broadcasting, Federal Communications Commission,
   Hydromatic, abalienation, account, acquaintance, alienation,
   amortization, amortizement, announcement, assignation, assignment,
   automatic transmission, bargain and sale, barter, bequeathal,
   blue book, briefing, broadcast, broadcasting, bulletin, carrying,
   cession, cogwheel, communication, communique, conduction,
   conferment, conferral, consignation, consignment, contagion,
   convection, conveyance, conveyancing, data, datum, deeding,
   deliverance, delivery, demise, deportation, diapedesis,
   differential, differential gear, diffusion, directory, disclosure,
   dispatch, disposal, disposition, dissemination, enfeoffment,
   enlightenment, evidence, exchange, export, exportation, expulsion,
   extradition, facts, factual information, fade-out, familiarization,
   forwarding, freewheel, gear, gear train, gearbox, gearing,
   gearshift, gearwheel, gen, general information, giving, guidebook,
   handout, hard information, high, impartation, imparting,
   impartment, import, importation, incidental information, info,
   information, instruction, intelligence, interchange, intermediate,
   knowledge, lease and release, light, low, mention, message,
   metastasis, metathesis, metempsychosis, migration, mixing,
   movement, moving, mutual transfer, neutral, notice, notification,
   osmosis, overdrive, passage, passing over, perfusion, presentation,
   promotional material, proof, publication, publicity, rack,
   radiobroadcasting, release, report, reverse, sale, sending,
   settlement, settling, sharing, shipment, shipping, sidelight,
   spread, spreading, standard broadcasting, standard transmission,
   statement, stick shift, surrender, synchromesh, telecasting,
   telling, the dope, the goods, the know, the scoop, tone control,
   trading, transduction, transfer, transfer of property,
   transference, transferral, transfusion, transit, transition,
   translation, translocation, transmigration,
   transmigration of souls, transmittal, transmittance, transmitting,
   transplacement, transplantation, transport, transportation,
   transporting, transposal, transposition, travel,
   vestigial transmission, vesting, volume control, white book,
   white paper, word



Bouvier's Law Dictionary, Revised 6th Ed (1856):

TRANSMISSION, civ. law. The right which heirs or legatees may have of
passing to their successors, the inheritance or legacy to which they were
entitled, if they happen to die without having exercised their rights.
Domat, liv. 3, t. 1, s. 10; 4 Toull. n. 186; Dig. 50, 17, 54; Code, 6, 51.