a social group composed of individuals of approximately the same age 
WordReference Random House Unabridged Dictionary of American English © 2025
peer′ group′, 
- Psychology, Sociologya group of people, usually of similar age, background, and social status, with whom a person associates and who are likely to influence the person's beliefs and behavior.
 
- 1940–45
 
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'peer group' also found in these entries (note: many are not synonyms or translations):