The Collaborative International Dictionary of English v.0.48:

Investiture \In*ves"ti*ture\ (?; 135), n. [LL. investitura: cf.
   F. investiture.]
   [1913 Webster]
   1. The act or ceremony of investing, or the state of being
      invested, as with an office; a giving possession; also,
      the right of so investing.
      [1913 Webster]

            He had refused to yield up to the pope the
            investiture of bishops.               --Sir W.
                                                  Raleigh.
      [1913 Webster]

   2. (Feudal Law) Livery of seizin.
      [1913 Webster]

            The grant of land or a feud was perfected by the
            ceremony of corporal investiture, or open delivery
            of possession.                        --Blackstone.
      [1913 Webster]

   3. That with which anyone is invested or clothed; investment;
      clothing; covering.
      [1913 Webster]

            While we yet have on
            Our gross investiture of mortal weeds. --Trench.
      [1913 Webster]

WordNet (r) 3.0 (2006):

investiture
    n 1: the ceremony of installing a new monarch [syn:
         coronation, enthronement, enthronization,
         enthronisation, investiture]
    2: the ceremonial act of clothing someone in the insignia of an
       office; the formal promotion of a person to an office or rank
       [syn: investment, investiture]

Moby Thesaurus II by Grady Ward, 1.0:

114 Moby Thesaurus words for "investiture":
   accedence, acceptance, accession, accommodation, accordance,
   admission, admittance, anchorage, apostolic orders, apparel,
   appointment, array, attire, award, awarding, baptism, bedizenment,
   bestowal, bestowment, calling, canonization, clothes, clothing,
   colonization, communication, concession, conferment, conferral,
   consecration, contribution, coronation, costume, deliverance,
   delivery, donation, drapery, dress, dressing, duds, election,
   endowment, enlistment, enrollment, enthronement, establishment,
   fashion, fatigues, feathers, fig, fixation, foundation,
   furnishment, garb, garments, gear, gifting, giving, grant,
   granting, guise, habiliment, habit, holy orders, immission,
   impartation, impartment, inaugural, inauguration, induction,
   initiation, installation, installment, instatement, institution,
   intromission, investment, liberality, linen, lodgment,
   major orders, minor orders, mooring, nomination, offer, ordainment,
   orders, ordination, peopling, placement, plantation, population,
   presentment, provision, rags, raiment, reading in, robes,
   settlement, settling, sportswear, style, subscription, supplying,
   surrender, taking office, threads, togs, toilette, trim, vestment,
   vesture, vouchsafement, wear, wearing apparel



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

INVESTITURE, estates. The act of giving possession of lands by actual seisin
When livery of seisin was made to a person by the common law he was invested
with the whole fee; this, the foreign feudists and sometimes 'our own law
writers call investiture, but generally speaking, it is termed by the common
law writers, the seisin of the fee. 2 Bl. Com. 209, 313; Feame on Rem. 223,
n. (z).
     2. By the canon law investiture was made per baculum et annulum, by the
ring and crosier, which were regarded as symbols of the episcopal
jurisdiction. Ecclesiastical and secular fiefs were governed by the same
rule in this respect that previously to investiture, neither a bishop, abbey
or lay lord could take possession of a fief. conferred upon them previously
to investiture by the prince.
     3. Pope Gregory VI. first disputed the right of sovereigns to give
investiture of ecclesiastical fiefs, A. D. 1045, but Pope Gregory VII.
carried. on the dispute with much more vigor, A. D. 1073. He excommunicated
the emperor, Henry IV. The Popes Victor III., Urban II. and Paul II.,
continued the contest. This dispute, it is said, cost Christendom sixty-
three battles, and the lives of many millions of men. De Pradt.