ˌcommon deˈnominator BrE AmE noun [countable]
1 . an attitude or quality that all the different members of a group have:
The common denominator of both types of novel is the vulnerable threatened heroine.
2 . the lowest common denominator the least attractive, least intelligent people or features in a situation:
trashy TV programs that appeal to the lowest common denominator
3 . technical a number that can be divided exactly by all the ↑ denominator s (=bottom number) in a set of ↑ fraction s