- sincerity
- 1546, from M.Fr. sincérité (1519), 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
- 1533, from M.Fr. sincere, from L. sincerus (see sincerity). Sincerely in the subscription of letters is attested from 1702.