The Collaborative International Dictionary of English v.0.48:

Dignity \Dig"ni*ty\, n.; pl. Dignities. [OE. dignete, dignite,
   OF. dignet['e], dignit['e], F. dignit['e], fr. L. dignitas,
   from dignus worthy. See Dainty, Deign.]
   1. The state of being worthy or honorable; elevation of mind
      or character; true worth; excellence.
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   2. Elevation; grandeur.
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            The dignity of this act was worth the audience of
            kings.                                --Shak.
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   3. Elevated rank; honorable station; high office, political
      or ecclesiastical; degree of excellence; preferment;
      exaltation. --Macaulay.
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            And the king said, What honor and dignity hath been
            done to Mordecai for this?            --Esth. vi. 3.
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            Reuben, thou art my firstborn, . . . the excellency
            of dignity, and the excellency of power. --Gen.
                                                  xlix. 3.
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   4. Quality suited to inspire respect or reverence; loftiness
      and grace; impressiveness; stateliness; -- said of mien,
      manner, style, etc.
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            A letter written with singular energy and dignity of
            thought and language.                 --Macaulay.
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   5. One holding high rank; a dignitary.
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            These filthy dreamers . . . speak evil of dignities.
                                                  --Jude. 8.
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   6. Fundamental principle; axiom; maxim. [Obs.]
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            Sciences concluding from dignities, and principles
            known by themselves.                  --Sir T.
                                                  Browne.

   Syn: See Decorum.
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   To stand upon one's dignity, to have or to affect a high
      notion of one's own rank, privilege, or character.
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            They did not stand upon their dignity, nor give
            their minds to being or to seeming as elegant and as
            fine as anybody else.                 --R. G. White.
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WordNet (r) 3.0 (2006):

dignity
    n 1: the quality of being worthy of esteem or respect; "it was
         beneath his dignity to cheat"; "showed his true dignity
         when under pressure" [syn: dignity, self-respect,
         self-regard, self-worth]
    2: formality in bearing and appearance; "he behaved with great
       dignity" [syn: dignity, lordliness, gravitas]
    3: high office or rank or station; "he respected the dignity of
       the emissaries"

Moby Thesaurus II by Grady Ward, 1.0:

187 Moby Thesaurus words for "dignity":
   Atticism, Establishment, VIP, address, appropriateness, augustness,
   baron, big gun, big man, big name, bigwig, brass, brass hat,
   buckram, cachet, celebrity, ceremonial, ceremoniousness, ceremony,
   chasteness, chastity, clarity, classicalism, classicism, clearness,
   comeliness, consequence, correctness, courtliness, decency,
   dignifiedness, dignitary, directness, discrimination, distinction,
   ease, elder, elegance, elegancy, elevation, eminence, esteem,
   ethicalness, ethics, etiquette, excellence, extrinsicality, face,
   fame, father, felicitousness, felicity, figure, finish,
   fittingness, flow, flowing periods, fluency, form, formality,
   formalization, glory, good taste, grace, gracefulness, gracility,
   grandeur, grandness, gravity, great man, greatness, hauteur,
   high place, honor, honorableness, impersonality, importance,
   important person, interests, kingliness, kudos, level, limpidity,
   lion, loftiness, lordliness, lords of creation, lucidity, magnate,
   magnificence, majesty, man of mark, memorability, merit, mogul,
   morality, nabob, name, naturalness, neatness, nobility, nobleness,
   notability, notable, noteworthiness, panjandrum, pellucidity,
   perfection, person of renown, personage, personality, perspicuity,
   pillar of society, plainness, poise, polish, pomp, pomposity,
   position, power, power elite, prestige, pride, pride of bearing,
   pride of place, primness, princeliness, prominence, propriety,
   proud bearing, purity, rank, refinement, regality, remarkableness,
   renown, reputation, repute, respectability, restraint, rigidness,
   ritual, rituality, ruling circle, sachem, salience, sedateness,
   seemliness, self-confidence, self-esteem, self-importance,
   self-regard, self-respect, simplicity, smoothness, sobriety,
   solemnity, somebody, something, standing, starchiness, state,
   stateliness, station, stature, status, stiffness, stiltedness,
   straightforwardness, stylization, sublimity, taste, tastefulness,
   terseness, the great, the top, top brass, top people, tycoon,
   unaffectedness, venerability, very important person, virtue,
   weight, worth, worthiness, worthy