The Collaborative International Dictionary of English v.0.48:

Roman \Ro"man\, a. [L. Romanus, fr. Roma Rome: cf. F. romain.
   Cf. Romaic, Romance, Romantic.]
   1. Of or pertaining to Rome, or the Roman people; like or
      characteristic of Rome, the Roman people, or things done
      by Romans; as, Roman fortitude; a Roman aqueduct; Roman
      art.
      [1913 Webster]

   2. Of or pertaining to the Roman Catholic religion;
      professing that religion.
      [1913 Webster]

   3. (Print.)
      (a) Upright; erect; -- said of the letters or kind of type
          ordinarily used, as distinguished from Italic
          characters.
      (b) Expressed in letters, not in figures, as I., IV., i.,
          iv., etc.; -- said of numerals, as distinguished from
          the Arabic numerals, 1, 4, etc.
          [1913 Webster]

   Roman alum (Chem.), a cubical potassium alum formerly
      obtained in large quantities from Italian alunite, and
      highly valued by dyers on account of its freedom from
      iron.

   Roman balance, a form of balance nearly resembling the
      modern steelyard. See the Note under Balance, n., 1.

   Roman candle, a kind of firework (generally held in the
      hand), characterized by the continued emission of shower
      of sparks, and the ejection, at intervals, of brilliant
      balls or stars of fire which are thrown upward as they
      become ignited.

   Roman Catholic, of, pertaining to, or the religion of that
      church of which the pope is the spiritual head; as, a
      Roman Catholic priest; the Roman Catholic Church.

   Roman cement, a cement having the property of hardening
      under water; a species of hydraulic cement.

   Roman law. See under Law.

   Roman nose, a nose somewhat aquiline.

   Roman ocher, a deep, rich orange color, transparent and
      durable, used by artists. --Ure.

   Roman order (Arch.), the composite order. See Composite,
      a., 2.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Roman Catholic
    adj 1: of or relating to or supporting Romanism; "the Roman
           Catholic Church" [syn: Roman, R.C., Romanist,
           romish, Roman Catholic, popish, papist,
           papistic, papistical]
    n 1: a member of the Roman Catholic Church
    2: the Christian Church based in the Vatican and presided over
       by a pope and an episcopal hierarchy [syn: Roman Catholic,
       Western Church, Roman Catholic Church, Church of Rome,
       Roman Church]