cohort

1. (statistics) A demographic grouping of people, especially those in a defined age group, or having a common characteristic.Examples: "The 18–24 cohort shows a sharp increase in automobile fatalities over the proximate age groupings."; "The elderly are market segments, by generations or microgenerations within age cohorts or by historical experience as personality types."; "“Zillennials refer to a small cohort born between the early 1990s and the early 2000s,” said Deborah Carr, professor of sociology and director of the Center for Innovation in Social Science at Boston University. “They’re on the cusp of Gen Z and millennial, thus the mash-up label of zillennial.”"

2. (historical, Ancient Rome, military) Any division of a Roman legion, normally of about 500 or 600 men (equalling about six centuries).Examples: "Holonym: legion"; "Meronyms: maniple, century"; "Three cohorts of men were assigned to the region."Ancient-Romehistorical

3. (taxonomy) A natural group of orders of organisms, less comprehensive than a class.