T Normal Ill he word "normal" comes from a Latin term meaning perpendicular o r at right angles. By the nineteenth century, it had come to mean regular o r usual, done by the rule o r on the square, not deviating from the common type or standard. In modern chemistry and physics, "normal" has a specific technical application having to do with statistical averages or means. But over time the word has also taken on a moral and quasi-medical status that confuses the "average" o r "mean" with the right, true, or appropriate.