Merriam-Webster's Collegiate Dictionary
sin·cer·i·ty
\\-ˈser-ə-tē, -ˈsir-\\ noun DATE 15th century
: the quality or state of being sincere
: honesty of mind
: freedom from hypocrisy
sincerity
1540s, from M.Fr. sincérité (early 16c.), from L. sinceritatem (nom. sinceritas), from sincerus "sound, pure, whole," perhaps originally "of one growth" (i.e. "not hybrid, unmixed"), from sem-, sin- "one" + root of crescere "to grow" (see crescent). Ground sense is of "that which is not falsified."
Oxford Collocations Dictionary for Students of English
Oxford Collocations dictionary for students of Englishsincerity
noun
ADJ. complete, deep, great, total | genuine, passionate | apparent ‘It's wonderful,’ he said with apparent sincerity.
VERB + SINCERITY doubt, mistake, question There seems no reason to doubt the sincerity of his beliefs. There was no mistaking his sincerity. | be convinced of She wasn't yet convinced of his sincerity. | demonstrate, prove, show
PREP. with ~
Webster's Third New International Dictionary, Unabridged
sin·cer·i·ty
\sənˈserəd.ē, -ˈsir-, -rətē, -i\ noun
(-es)
Etymology: Middle French sincerité, from Latin sinceritat-, sinceritas, from sincerus sincere + -itat-, -itas -ity
1. : the quality or state of being sincere
< the passionate sincerity of artists and other intellectuals may still be warped by wishful preferences — H.J.Muller >
2.
a. : a sincere feeling
< grounded not on garnitures and semblances but on realities and sincerities — Thomas Carlyle >
b. : an expression of a sincere feeling
< his voice altered and ceased to sing its pleasantly tuned sincerities — Nancy Keesing >