The Collaborative International Dictionary of English v.0.48:

conformist \conformist\ adj.
   1. marked by conformity or convention; not corresponding to
      current customs or rules or styles; as, underneath the
      radical image teenagers are surprisingly conformist.
      Opposite of nonconformist.
      [WordNet 1.5]

   2. same as conforming.

   Note: [Narrower terms: orthodox (vs. unorthodox)]

   Syn: conforming.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Conformist \Con*form"ist\, n.
   One who conforms or complies; esp., one who conforms to the
   Church of England, or to the Established Church, as
   distinguished from a dissenter or nonconformist.
   [1913 Webster]

         A cheeful conformist to your judgment.   --Jer.Taylor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

conformist
    adj 1: marked by convention and conformity to customs or rules
           or styles; "underneath the radical image teenagers are
           surprisingly conformist" [ant: nonconformist,
           unconformist]
    2: adhering to established customs or doctrines (especially in
       religion) [syn: conforming, conformist]
    n 1: someone who conforms to established standards of conduct
         (especially in religious matters) [ant: nonconformist,
         recusant]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "conformist":
   Babbitt, Grundy, Middle American, Philistine, anal character, ape,
   bourgeois, burgher, compulsive character, conformer,
   conventionalist, copier, copycat, copyist, counterfeiter, cuckoo,
   dissembler, dissimulator, echo, echoer, echoist, faker, forger,
   formalist, hypocrite, imitator, impersonator, impostor,
   methodologist, middle-class type, mime, mimer, mimic, mimicker,
   mocker, mockingbird, model child, monkey, organization man, parrot,
   pedant, perfectionist, phony, plagiarist, plastic person,
   poll-parrot, polly, polly-parrot, poseur, precisian, precisianist,
   sheep, simulator, square, teenybopper, trimmer, yes-man