The term 'Go Round the Bend' is an idiom that means to become insane or to lose one's temper. It is derived from the phrase 'to go round the bend, ' which was used to describe a sharp TURN in a river. The crossword solutions for this term are 'TURN, ' which is a four-letter word. This solution is appropriate because it implies that someone has gone off the deep end and has taken a sharp TURN in their behavior.