[1] : The Collaborative International Dictionary of English v.0.48

self-importance \self`-impor"tance\, n.
   an exaggerated estimate of one's own importance or merit,
   esp. as manifested by the conduct or manners; self-conceit.
   1913 webster

[2] : WordNet (r) 2.0

self-importance
     n 1: an inflated feeling of pride in your superiority to others
          syn: ego, egotism
     2: an exaggerated opinion of your own importance syn: egotism,
         swelled head
see also:
ego egotism swelled head 

[3] : Moby Thesaurus II by Grady Ward, 1.0

98 moby thesaurus words for "self-importance":
   accent, amour-propre, arrogance, assurance, assuredness,
   autoeroticism, belief, certitude, cocksureness, complacency,
   concern, concernment, confidence, confidentness, consequence,
   consequentiality, consideration, conviction, courage, ego trip,
   egoism, egotism, emphasis, excellence, faith, grandiloquence,
   high order, high rank, hubris, import, importance, inflation,
   interest, mark, materiality, merit, moment, narcism, narcissism,
   note, orotundity, overconfidence, overproudness, oversureness,
   overweening, overweening pride, overweeningness, paramountcy,
   poise, pomposity, pompousness, pontificality, pontification,
   positiveness, precedence, preeminence, pride, primacy, priority,
   security, self-admiration, self-approbation, self-assurance,
   self-complacency, self-confidence, self-congratulation,
   self-consequence, self-content, self-delight, self-endearment,
   self-esteem, self-gratulation, self-infatuation, self-love,
   self-reliance, self-respect, self-satisfaction, self-sufficiency,
   self-worship, settled belief, significance, smugness, stress,
   stuffiness, subjective certainty, superiority, supremacy, sureness,
   surety, trust, turgidity, vaingloriousness, vainglory, vainness,
   value, vanity, weight, worth

Self-Importance >> S Words
Self-Importance, definition of term: Self-Importance
self-importance_pag1.html