Other forms: couthly
Couth is an adjective that means "refined or well mannered," like a couth gentleman who stands every time a woman leaves or returns to the table at the fancy dinner — the poor guy got a workout!
As a noun, couth means good manners, sophistication or politeness, like having the couth to hold the door — or hold your tongue if the conversation turns to touchy subjects like money, politics, religion, or a person's physical appearance. The opposite of couth is uncouth. Around such a person, expect doors to slam in faces and uncomfortable conversations about sensitive matters.