The Collaborative International Dictionary of English v.0.48:

Sententious \Sen*ten"tious\, a.[L. sentenciosus: cf. F.
   sentencieux.]
   1. Abounding with sentences, axioms, and maxims; full of
      meaning; terse and energetic in expression; pithy; as, a
      sententious style or discourse; sententious truth.
      [1913 Webster]

            How he apes his sire,
            Ambitiously sententious!              --Addison.
      [1913 Webster]

   2. Comprising or representing sentences; sentential. [Obs.]
      "Sententious marks." --Grew.
      [1913 Webster] -- Sen*ten"tious*ly, adv. --
      Sen*ten"tious*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sententious
    adj 1: abounding in or given to pompous or aphoristic
           moralizing; "too often the significant episode
           deteriorates into sententious conversation"- Kathleen
           Barnes
    2: concise and full of meaning; "welcomed her pithy comments";
       "the peculiarly sardonic and sententious style in which Don
       Luis composed his epigrams"- Hervey Allen [syn: pithy,
       sententious]

Moby Thesaurus II by Grady Ward, 1.0:

150 Moby Thesaurus words for "sententious":
   Gongoresque, Johnsonian, Spartan, abbreviated, abridged,
   admonitory, advisory, affected, allegorical, aphoristic,
   aposiopestic, associational, axiomatic, bedizened, big-sounding,
   brief, brusque, cautionary, clipped, close, compact, compendious,
   compressed, concise, condensed, connotational, connotative,
   consultative, consultatory, contracted, convoluted, crisp, curt,
   cut, declamatory, definable, denotational, denotative, didactic,
   directive, docked, elevated, elliptic, eloquent, epigrammatic,
   euphuistic, exhortative, exhortatory, expostulative, expostulatory,
   expressive, extended, extensional, facund, figurative, flamboyant,
   flaming, flashy, flaunting, formulaic, formulistic,
   full of meaning, full of point, full of substance, fulsome, garish,
   gaudy, gnomic, grandiloquent, grandiose, grandisonant,
   high-flowing, high-flown, high-flying, high-sounding, highfalutin,
   hortative, hortatory, indicative, inkhorn, instructive,
   intelligible, intensional, interpretable, labyrinthine, laconic,
   lexiphanic, lofty, lurid, magniloquent, meaning, meaningful, meaty,
   meretricious, metaphorical, monitorial, monitory, moralistic,
   orotund, ostentatious, overdone, overelaborate, overinvolved,
   overwrought, pedantic, piquant, pithy, platitudinous, pointed,
   pompous, preachy, pregnant, pretentious, proverbial, pruned,
   pungent, readable, recommendatory, referential, remonstrant,
   remonstrative, remonstratory, reserved, rhetorical, rich,
   sensational, sensationalistic, short, short and sweet, shortened,
   showy, significant, significative, sonorous, stilted, substantial,
   succinct, suggestive, summary, symbolic, synopsized, taciturn,
   tall, terse, tight, to the point, tortuous, transferred, truncated,
   warning