Correctitude is the state of behaving in a very proper way — the right clothes, the right manners, the right words, nothing out of line. It is a rare, slightly old-fashioned noun. When it appears, there is often a raised eyebrow in it: not just “good manners,” but a stiffness, a person who is almost too correct. You would not ask for “more correctitude” in daily life. You might find it in a novel or a dry joke about someone who never puts a foot wrong, and perhaps never has much fun either. Though actually, it is built in a simple way from correct, so the meaning is not mysterious; it is only that almost nobody reaches for this noun any more. Rectitude is the cousin you are more likely to meet, and that one is about moral uprightness, not table manners.