The term 'HEAD'S OPPOSITE' can be solved by two different crossword solutions: TAIL (4 letters) and TOE (3 letters). The term 'HEAD's opposite' is a phrase used to describe the opposite of the HEAD, which is the topmost part of the body. The first solution, TAIL, refers to the appendage found on the lower end of many animals, including cats, dogs, and monkeys. The second solution, TOE, refers to the digits found at the end of the feet of humans and other animals.