The Collaborative International Dictionary of English v.0.48:

Doctrinaire \Doc`tri*naire"\, n. [F. See Doctrine.]
   One who would apply to political or other practical concerns
   the abstract doctrines or the theories of his own
   philosophical system; a propounder of a new set of opinions;
   a dogmatic theorist. Used also adjectively; as, doctrinaire
   notions.
   [1913 Webster]

   Note: In french history, the Doctrinaires were a
         constitutionalist party which originated after the
         restoration of the Bourbons, and represented the
         interests of liberalism and progress. After the
         Revolution of July, 1830, when they came into power,
         they assumed a conservative position in antagonism with
         the republicans and radicals. --Am. Cyc.
         [1913 Webster]

WordNet (r) 3.0 (2006):

doctrinaire
    adj 1: stubbornly insistent on theory without regard for
           practicality or suitability
    n 1: a stubborn person of arbitrary or arrogant opinions [syn:
         dogmatist, doctrinaire]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "doctrinaire":
   antiblack, armchair authority, authoritarian, authoritative,
   biased, bigot, bigoted, bullheaded, chauvinist, chauvinistic,
   colored, conceited, doctrinarian, dogged, dogmatic, dogmatist,
   dogmatizer, dogmatizing, fanatic, hypothesist, hypothesizer,
   illiberal, infallibilist, influenced, interested, intolerant,
   jaundiced, jingo, know-nothing, magisterial, male chauvinist,
   mulish, nonobjective, obstinate, one-sided, opinionated,
   opinionative, opinioned, opinionist, oracular, partial, partisan,
   peremptory, pertinacious, pig, pigheaded, pontifical, positive,
   positivist, positivistic, prejudiced, prepossessed, pronunciative,
   racist, self-opinionated, self-opinioned, sexist, speculator,
   stiff-necked, stubborn, superpatriot, superpatriotic, swayed,
   theoretic, theoretician, theorist, theorizer, twisted,
   ultranationalist, undetached, undispassionate, warped,
   xenophobic