Decimal BASIS is a term used to describe the numerical system of counting in which the base is 10. This system is also known as the base-10 system and is the most widely used system in the world today. The term DECIMAL BASIS is made up of three words: TEN, DECIMAL, and BASIS. TEN is a three letter word meaning the number 10. DECIMAL is an eight letter word referring to the base-10 system of counting. BASIS is a five letter word meaning the foundation or starting point.