The Collaborative International Dictionary of English v.0.48:

Empiric \Em*pir"ic\, Empirical \Em*pir"ic*al\, a.
   1. Pertaining to, or founded upon, experiment or experience;
      depending upon the observation of phenomena; versed in
      experiments.
      [1913 Webster]

            In philosophical language, the term empirical means
            simply what belongs to or is the product of
            experience or observation.            --Sir W.
                                                  Hamilton.
      [1913 Webster]

            The village carpenter . . . lays out his work by
            empirical rules learnt in his apprenticeship. --H.
                                                  Spencer.
      [1913 Webster]

   2. Depending upon experience or observation alone, without
      due regard to science and theory; -- said especially of
      medical practice, remedies, etc.; wanting in science and
      deep insight; as, empiric skill, remedies.
      [1913 Webster]

   Empirical formula. (Chem.) See under Formula.

   Syn: See Transcendental.
        [1913 Webster]

WordNet (r) 3.0 (2006):

empirical
    adj 1: derived from experiment and observation rather than
           theory; "an empirical basis for an ethical theory";
           "empirical laws"; "empirical data"; "an empirical
           treatment of a disease about which little is known" [syn:
           empirical, empiric] [ant: theoretic, theoretical]
    2: relying on medical quackery; "empiric treatment" [syn:
       empiric, empirical]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "empirical":
   Cyrenaic, Eleatic, Epicurean, Megarian, Stoic, animist, animistic,
   atomistic, cosmotheistic, cut-and-try, eclectic, eudaemonistic,
   existential, experiential, experimental, factual, hedonic,
   hedonist, hedonistic, heuristic, hit-or-miss, humanist, humanistic,
   idealistic, instrumentalist, materialistic, mechanistic,
   metaphysical, monistic, naturalistic, nominalist, observed,
   panlogistical, pantheistic, pilot, positivist, positivistic,
   practical, pragmatic, pragmatist, probationary, probative,
   probatory, proving, provisional, rationalistic, realist, realistic,
   scholastic, sensationalistic, syncretistic, tentative, test,
   testing, theistic, transcendentalist, transcendentalistic, trial,
   trial-and-error, trying, utilitarian, verificatory, vitalistic,
   voluntarist, voluntaristic