The Collaborative International Dictionary of English v.0.48:

Chaperon \Chap"er*on\, n. [F. chaperon. See Chape, Cape,
   Cap.]
   1. A hood; especially, an ornamental or an official hood.
      [1913 Webster]

            His head and face covered with a chaperon, out of
            which there are but two holes to look through.
                                                  --Howell.
      [1913 Webster]

   2. A device placed on the foreheads of horses which draw the
      hearse in pompous funerals.
      [1913 Webster]

   3. A matron who accompanies a young lady in public, for
      propriety, or as a guide and protector.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Chaperon \Chap"er*on\, v. t. [imp. & p. p. Chaperoned; p. pr.
   & vb. n. Chaperoning.] [Cf. F. chaperonner, fr. chaperon.]
   To attend in public places as a guide and protector; to
   matronize.
   [1913 Webster]

         Fortunately Lady Bell Finley, whom I had promised to
         chaperon, sent to excuse herself.        --Hannah More.
   [1913 Webster]

WordNet (r) 3.0 (2006):

chaperon
    n 1: one who accompanies and supervises a young woman or
         gatherings of young people [syn: chaperon, chaperone]
    v 1: accompany as a chaperone [syn: chaperone, chaperon]

Moby Thesaurus II by Grady Ward, 1.0:

96 Moby Thesaurus words for "chaperon":
   abigail, amah, attend, attend to, au pair girl, ayah, baby-sit,
   bear, betweenmaid, biddy, bodyguard, boss, bring, care for, carry,
   cavalier, chambermaid, cherish, companion, conduct, conductor,
   conserve, consort with, convoy, cook, duenna, escort, esquire,
   fellow traveler, femme de chambre, fille de chambre, foster,
   gentlewoman, girl, governess, guard, guide, handmaid, handmaiden,
   hired girl, housemaid, keep watch over, kitchenmaid, lady-help,
   lady-in-waiting, lead, live-in maid, live-out maid, look after,
   look out for, look to, maid, maidservant, marshal, matronize, mind,
   minister to, mother, nurse, nursemaid, nurture, overlook, oversee,
   parlormaid, preserve, protege, provide for, quarterback,
   ride herd on, safe-conduct, scullery maid, see after, see to,
   servant girl, servitress, shepherd, soubrette, squire, superintend,
   supervise, support, survey, swain, take care of, take charge of,
   take out, tend, tweeny, upstairs maid, usher, wait on,
   waiting maid, watch, watch out for, watch over, wench