Adjective used to describe someone who is especially ignorant, i.e. when simply saying that a particular person is ignorant won't fully convey just how ignorant they are.
Person 1: Hey, Jane lost weight, she must be on drugs, she must not have any teeth.
Person 2: No ignant, Jane works out everyday and watches what she eats! She has a beautiful smile with perfect teeth to match (ALL HER TEETH), you are such a hater.