Adj. fem. Demographics ( evaluation of the inhabitants according to their activities, age, instruction, etc ) quantification of the population by age ranges, most commonly by steps of five years: 1 ) up to five; 2 ) between five and ten; 3 ) between ten and fifteen, and so forth. Derived from the Latin noun "Aeta, aetatis" cases nominative and genitive singular equivalent to "age of the age", and the ending "Aryan", indicative of grouping, set.