The Collaborative International Dictionary of English v.0.48:

Dominican \Do*min"i*can\, prop. a. [NL. Dominicanus, fr.
   Dominicus, Dominic, the founder: cf. F. Dominicain.]
   Of or pertaining to St. Dominic (Dominic de Guzman), or to
   the religious communities named from him.
   [1913 Webster]

   Dominican nuns, an order of nuns founded by St. Dominic,
      and chiefly employed in teaching.

   Dominican tertiaries the third order of St. Dominic. See
      Tertiary.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dominican \Do*min"i*can\, prop. n. (Eccl. Hist.)
   One of an order of mendicant monks founded by Dominic de
   Guzman, in 1215. A province of the order was established in
   England in 1221. The first foundation in the United States
   was made in 1807. The Master of the Sacred Palace at Rome is
   always a Dominican friar. The Dominicans are called also
   preaching friars, friars preachers, black friars (from
   their black cloak), brothers of St. Mary, and in France,
   Jacobins.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Dominican
    adj 1: of or relating to or characteristic of the Dominican
           Republic or its people; "the Dominican population"
    2: of or relating to Saint Dominic or the Dominican order;
       "Dominican monks"
    n 1: a Roman Catholic friar wearing the black mantle of the
         Dominican order [syn: Dominican, Black Friar,
         Blackfriar, friar preacher]
    2: a native or inhabitant of the Dominican Republic

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "Dominican":
   Augustinian, Augustinian Hermit, Austin Friar, Benedictine,
   Bernardine, Black Friar, Black Monk, Bonhomme, Brigittine,
   Capuchin, Carmelite, Carthusian, Cistercian, Cluniac, Conventual,
   Crossed Friar, Crutched Friar, Franciscan, Friar Minor, Gilbertine,
   Gray Friar, Hospitaler, Jesuit, Loyolite, Marist, Maryknoll,
   Minorite, Observant, Oratorian, Premonstratensian, Recollect,
   Recollet, Redemptorist, Templar, Trappist, White Friar,
   begging hermit, preaching friar