The Collaborative International Dictionary of English v.0.48:

Apologetic \A*pol`o*get"ic\, Apologetical \A*pol`o*get"ic*al\,
   a. [Gr. ?, fr. ? to speak in defense of; ? from + ? speech, ?
   to say, to speak. See Logic.]
   Defending by words or arguments; said or written in defense,
   or by way of apology; regretfully excusing; as, an apologetic
   essay. "To speak in a subdued and apologetic tone."
   --Macaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

apologetic
    adj 1: offering or expressing apology; "an apologetic note"; "an
           apologetic manner" [syn: apologetic, excusatory]
           [ant: unapologetic]

Moby Thesaurus II by Grady Ward, 1.0:

60 Moby Thesaurus words for "apologetic":
   abject, apologia, ascetic, atoning, cleansing, compensational,
   compensatory, compunctious, conscience-stricken, contrite, defense,
   excusatory, excusing, expiatory, extenuating, extenuative, humble,
   humbled, justification, justificatory, justifying, lustral,
   lustrational, lustrative, melted, palliative, penitent,
   penitential, penitentiary, piacular, propitiatory, purgative,
   purgatorial, purifying, reclamatory, recompensing, redeeming,
   redemptive, redressing, refuting, regretful, rehabilitative,
   remorseful, reparative, reparatory, repentant, repenting,
   restitutional, restitutive, restitutory, righting, rueful,
   satisfactional, sheepish, softened, sorry, squaring, touched,
   vindicative, vindicatory