The word "sincere" doesn't have a prefix in the traditional sense. It comes from the Latin "sine" (without) and "cerus" (wax), referring to the ancient practice of testing the purity of gold by rubbing it on a black stone. If the gold was pure, it would leave a mark without any wax residue. So, "sincere" literally means "without wax" and evolved to mean "genuine" or "honest."
