Source : Webster's Revised Unabridged Dictionary (1913)

Asseveration \As*sev`er*a"tion\, n. [L. asseveratio.]
   The act of asseverating, or that which is asseverated;
   positive affirmation or assertion; solemn declaration.

         Another abuse of the tongue I might add, -- vehement
         asseverations upon slight and trivial occasions. --Ray.

Source : WordNet®

asseveration
     n : a declaration that is made emphatically (as if no supporting
         evidence were necessary) [syn: {assertion}, {averment}]