The Collaborative International Dictionary of English v.0.48:

Chair \Chair\, v. t. [imp. & p. p. Chaired; p. pr. & vb. n.
   Chairing.]
   1. To place in a chair.
      [1913 Webster]

   2. To carry publicly in a chair in triumph. [Eng.]
      [1913 Webster]

   3. To function as chairperson of (a meeting, committee,
      etc.); as, he chaired the meeting.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Chair \Chair\ (ch[^a]r), n. [OE. chaiere, chaere, OF. chaiere,
   chaere, F. chaire pulpit, fr. L. cathedra chair, armchair, a
   teacher's or professor's chair, Gr. ? down + ? seat, ? to
   sit, akin to E. sit. See Sit, and cf. Cathedral,
   chaise.]
   [1913 Webster]
   1. A movable single seat with a back.
      [1913 Webster]

   2. An official seat, as of a chief magistrate or a judge, but
      esp. that of a professor; hence, the office itself.
      [1913 Webster]

            The chair of a philosophical school.  --Whewell.
      [1913 Webster]

            A chair of philology.                 --M. Arnold.
      [1913 Webster]

   3. The presiding officer of an assembly; a chairman; as, to
      address the chair.
      [1913 Webster]

   4. A vehicle for one person; either a sedan borne upon poles,
      or two-wheeled carriage, drawn by one horse; a gig.
      --Shak.
      [1913 Webster]

            Think what an equipage thou hast in air,
            And view with scorn two pages and a chair. --Pope.
      [1913 Webster]

   5. An iron block used on railways to support the rails and
      secure them to the sleepers.
      [1913 Webster]

   Chair days, days of repose and age.

   To put into the chair, to elect as president, or as
      chairman of a meeting. --Macaulay.

   To take the chair, to assume the position of president, or
      of chairman of a meeting.
      [1913 Webster]

WordNet (r) 3.0 (2006):

chair
    n 1: a seat for one person, with a support for the back; "he put
         his coat over the back of the chair and sat down"
    2: the position of professor; "he was awarded an endowed chair
       in economics" [syn: professorship, chair]
    3: the officer who presides at the meetings of an organization;
       "address your remarks to the chairperson" [syn: president,
       chairman, chairwoman, chair, chairperson]
    4: an instrument of execution by electrocution; resembles an
       ordinary seat for one person; "the murderer was sentenced to
       die in the chair" [syn: electric chair, chair, death
       chair, hot seat]
    5: a particular seat in an orchestra; "he is second chair
       violin"
    v 1: act or preside as chair, as of an academic department in a
         university; "She chaired the department for many years"
         [syn: chair, chairman]
    2: preside over; "John moderated the discussion" [syn:
       moderate, chair, lead]

Moby Thesaurus II by Grady Ward, 1.0:

172 Moby Thesaurus words for "chair":
   Eames chair, Hitchcock chair, TV chair, administer, administrate,
   anoint, armchair, armless chair, authority, ax, back seat,
   banquette, bar stool, barber chair, barrel chair, basket chair,
   batwing chair, be master, bed chair, beheading, bench,
   bicycle seat, block, boudoir chair, bow-back chair, bucket seat,
   burning, camp chair, campaign chair, capital punishment, captain,
   chair of English, chairman, club chair, club lounge chair,
   comb-back chair, command, contour chair, convener, cricket,
   cricket chair, cross, crown, crucifixion, curule chair, dais,
   death chair, death chamber, decapitation, decollation,
   defenestration, dining chair, direct, directorship, discipline,
   draft chair, drop, easy chair, elbowchair, electric chair,
   electrocution, enthrone, execution, fan-back chair, fauteuil,
   fellowship, fender stool, folding chair, foldstool, form,
   fusillade, gallows, gallows-tree, garden chair, garrote,
   gas chamber, gassing, gibbet, govern, guillotine, halter, hanging,
   hassock, head, helm, hemlock, hemp, hempen collar, high chair,
   horse, hot seat, inaugurate, induct, install, instate, invest,
   judicial murder, ladder-back chair, lapidation, lead, leader,
   lethal chamber, maiden, manage, milking stool, moderate, moderator,
   necktie party, noose, occupy the chair, officer, officiate,
   ottoman, oversee, overstuffed chair, pew, place, place in office,
   platform rocker, poisoning, position, preceptorship, preside,
   preside over, presiding officer, professorate, professorhood,
   professoriate, professorship, put in, readership, regulate, rocker,
   rocking chair, rope, run, saddle, scaffold, schoolmastery, seat,
   seat of power, seat of state, sedan chair, settle, shooting,
   speaker, stake, stand over, step stool, stoning, stool, strangling,
   strangulation, supervise, swing, taboret, teachership, the ax,
   the block, the chair, the gallows, the gas chamber, the guillotine,
   the hot seat, the rope, throne, tree, tutelage, tutorage,
   tutorship, wield authority, woolsack