Many people use the phrase **least common denominator **to describe something as being base or common. It connotes something that appeals to most people, something that we all value. It is the *intersection *of what we all value, in the set-theory sense. But in arithmetic the LCD is the *union* of the prime factors of the denominators (including the multiplicity of those factors).

Perhaps **greatest common divisor **is a better metaphor for what is typically described as an LCD, the GCD being the intersection of prime factors.