Source : Webster's Revised Unabridged Dictionary (1913)

Sincerity \Sin*cer"i*ty\, n. [L. sinceritas: cf. F.
   sinc['e]rit['e].]
   The quality or state of being sincere; honesty of mind or
   intention; freedom from simulation, hypocrisy, disguise, or
   false pretense; sincereness.

         I protest, in the sincerity of love.     --Shak.

         Sincerity is a duty no less plain than important.
                                                  --Knox.

Source : WordNet®

sincerity
     n 1: an earnest and sincere feeling [syn: {earnestness}, {seriousness}]
     2: the quality of being open and truthful; not deceitful or
        hypocritical; "his sincerity inspired belief"; "they
        demanded some proof of my sincerity" [ant: {insincerity}]
     3: a quality of naturalness and simplicity; "the simple
        sincerity of folk songs" [syn: {unassumingness}]
     4: the trait of being serious; "a lack of solemnity is not
        necessarily a lack of seriousness"- Robert Rice [syn: {seriousness},
         {earnestness}, {serious-mindedness}] [ant: {frivolity}]