An ill-mannered one is someone who is rude and lacks good manners. This can be described in a variety of ways, such as CAD (3 letters), BOOR (4 letters), LOUT (4 letters) and OAF (3 letters). A CAD is someone who is unprincipled and deceitful, while a BOOR is someone who is rude and insensitive. A LOUT is someone who is uncouth and ill-mannered, and an OAF is someone who is clumsy and awkward. All of these terms describe someone who is ill-mannered and lacking in good manners.