sincerity Look up sincerity at Dictionary.com
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."
sincere Look up sincere at Dictionary.com
1530s, from M.Fr. sincere, from L. sincerus (see sincerity).