The term DECIMAL UNIT is composed of two words, TEN (3 letters) being the first. The word 'TEN' is a cardinal number that is used to represent the quantity of 10. It is the base of the decimal system, which is a system of counting and measuring that uses the number 10 as its base. The second word, 'UNIT', refers to a single thing or entity, such as a single item, a single person, or a single measurement. Together, the two words DECIMAL UNIT refer to a single UNIT of measurement in the decimal system.