The term 'YOU CAN BELIEVE IT' can be broken down into two crossword solutions: ISM (3 letters) and TENET (5 letters). ISM stands for 'Ideology, System, or Method' and is used to refer to a set of beliefs or principles that guide behavior. TENET is derived from the Latin word 'tenere, ' which means 'to hold.' It is used to refer to a principle, belief, or doctrine that is held to be true and is often used in religious contexts.