Cohort refers to a group of individuals sharing certain significant social characteristics in common, such as sex, time, and place of birth.
Other definition:
Cohort refers to a Group of individuals who are followed over time and who experience the same cultural or historical events during the same period of time.
Other /More definition:
Cohort may refer to:

(1) A group of participants starting an experience at the same time.

(2) A group of people of the same age who are exposed to similar cultural environments and historical events as they are growing up.

(3) A group of individuals sharing certain significant social characteristics in common, such as sex, time, and place of birth.
Other /More definition:
cohort refer to participants in each age group of a study with a cross-sectional design.