The term 'AS A MARCH HARE' can be summarized by the crossword solution MAD, which is an acronym for 'Mental Affective Disorder'. This term is used to describe a mental health condition characterized by extreme mood swings, difficulty in controlling emotions, and irrational behavior. It is often associated with the character of the March Hare from Lewis Carroll's Alice's Adventures in Wonderland, who is known for his erratic behavior.