The term 'You Better Believe It!' can be expressed in two crossword solutions: Yessiree (8 letters) and DOGMA (5 letters). Yessiree is an informal expression of agreement, often used to express enthusiasm or excitement. It is derived from the phrase 'Yes, sir!' and is commonly used in the Southern United States. DOGMA is a set of beliefs or principles that are accepted as true without question. It is often associated with religious beliefs, but it can also refer to any set of beliefs that are held to be unquestionably true.