cohort

noun

co·​hort ˈkō-ˌhȯrt 

1

: companion, colleague

… a few of their … cohorts decided to form a company …

—Burt Hochberg

2

a

: band, group

a cohort of supporters

b

: a group of individuals having a statistical factor (such as age or class membership) in common in a demographic study

a cohort of premedical students

the cohort of people born in the 1980s

c

: one of 10 divisions of an ancient Roman legion

d

: a group of warriors or soldiers

Did you know?

In ancient times, a cohort was a military unit, one of ten divisions in a Roman legion. The term passed into English in the 15th century, when it was used in translations and writings about Roman history. Once cohort became established in our language, its meaning was extended, first to refer to any body of troops, then to any group of individuals with something in common, and later to a single companion. Some usage commentators have objected to this last sense because it can be hard to tell whether the plural refers to different individuals or different groups. The "companion" sense is well established in standard use, however, and its meaning is clear enough in such sentences as "her cohorts came along with her to the game."

Synonyms of cohort

• associate
• colleague
• peer
• fellow
• friend
• buddy
• classmate
• accomplice

Examples of cohort in a Sentence

The police arrested the gang's leader and his cohorts.

Depression was a common problem for people in that age cohort.

Recent Examples on the Web

As a consequence, this list is likely to evolve when individuals from the current cohort of elderly billionaires, like investor Warren Buffet, pass away and distribute their fortunes to their children and extended families. —David Faris, TheWeek, 20 Mar. 2026

Plus, the cohort only included women 55 and over. —Helen Carefoot, Flow Space, 20 Mar. 2026

An international team of scientists pored over data from two large cohort studies involving more than 110,000 people whose physical activity was assessed over 30 years. —CNN Money, 19 Mar. 2026

This year’s speakers will be joined by our inaugural cohort of Semafor World Economy Principals — applications are now open here. —Rachel Keidan, semafor.com, 18 Mar. 2026

Word History

Etymology

Middle English, from Latin cohort-, cohors — more at court

First Known Use

15th century, in the meaning defined at sense 2c

Kids Definition

cohort

noun

co·​hort ˈkō-ˌhȯrt 

1

a

: one of 10 divisions of an ancient Roman legion

b

: a group of warriors or followers

2

: companion sense 1, accomplice

Medical Definition

cohort

noun

co·​hort ˈkō-ˌhȯ(ə)rt 

: a group of individuals having a statistical factor (as age or risk) in common

the population consisted of two cohorts: 204 clearly exposed and 163 not exposed

—R. R. Suskind et al.