Denominator (noun)

1. The bottom part of a fraction representing the number of equal parts into which a unit is divided.
2. A shared characteristic or common factor used to classify a group of things.

Origin:

Derived from the latin word 'denominare' meaning 'to name'.

Examples:

1. The denominator of the fraction is the number of parts the whole is divided into.
2. The denominator of the fraction 3/4 is 4.
3. The denominator in the expression of the rate is the time period.
4. Age and gender are common denominators used to categorize a population.
5. The denominator of a statistical calculation is used to normalize the results.