noun
1.
( NAmE usually ˌleast ˌcommon deˈnominator ) ( mathematics ) the smallest number that the bottom numbers of a group of fractions can be divided into exactly
2.
( NAmE also ˌleast ˌcommon deˈnominator ) ( disapproving ) something that is simple enough to seem interesting to, or to be understood by, the highest number of people in a particular group; the sort of people who are least intelligent or accept sth that is of low quality :
The school syllabus seems aimed at the lowest common denominator.