cohort

The word cohort originally comes from ancient Rome, where it referred to one-tenth of a legion—essentially a tactical unit of soldiers. While its military roots remain part of the definition, "cohort" has broadened significantly. Today, it primarily describes any group of people who share a common characteristic or experience, especially those moving through time together.

It is more than just a random collection of individuals; a cohort implies a shared journey and a degree of connection. For instance, all students who started kindergarten in the same year form a cohort because they experience school milestones simultaneously. Similarly, people born within the same era, such as Millennials or Gen Z, are often referred to as generational cohorts.

In business and statistics, "cohort analysis" is a vital practice. It involves tracking specific groups of users over time to understand their long-term behavior. A company might analyze a cohort of new subscribers to see how many continue using a service after six months compared to those who joined at a different time.

Beyond the group definition, cohort is also used in a more personal sense to mean a companion or close associate, often used in the plural as "his cohorts." Whether describing a military unit, a demographic group, or a trusted colleague, the word represents a bond formed by a common path, a shared task, or a specific moment in history.