Rouge is any kind of red or reddish-colored makeup that's used for tinting a person's cheeks. The word rouge can also refer to the red color itself, or it can be a verb, which you'd use to say, "Grandma, you're uneven — you forgot to rouge your left cheek." The root of rouge is the Latin word rubeus, which itself means "red". A common mistake is to confuse the words rouge and rogue, which means a scoundrel.