sincere

Sincere comes from Middle French sincere, from Latin sincerus, meaning "genuine." That in turn traces to Proto-Indo-European roots *sem- ("together") and *ḱer- ("grow"), the same *ḱer- that gave Latin Ceres, goddess of harvest, and later English cereal.

There's a popular story that sincere comes from Latin sine ("without") plus cera ("wax") — as if it described pottery without wax to hide cracks. That story is false; the real roots point instead to something grown together as one whole.

Sincere shares its *sem- root with English sam, and its *ḱer- root connects it, through Ceres, to cereal — so honesty and harvest grain turn out to be etymological cousins.