A Lack of Sensibility is a term used to describe the behavior of characters in Jane Austen's novel, 'SENSE and Sensibility'. The novel follows two sisters, Elinor and Marianne Dashwood, who have very different personalities. Elinor is known for her SENSE and sensibility, while Marianne is known for her lack of sensibility. This lack of sensibility is demonstrated through her impulsive behavior and disregard for social conventions.