"peer, n. and adj. A. 1. a. A person of the same civil or ecclesiastical status or rank as the person in question; an equal before the law. Frequently with possessive adjective and in plural. b. A person who equals another in natural gifts, ability, or achievements; the equal in any respect of a person or thing. c. orig. Cultural Anthropology and Sociology. A member of the same age group or social set; a contemporary. " OED

The term "peer" can refer to people and a process.

• The Knowledge Market has highly-trained fellow students or peers who can help you improve your skills. Peer consultants are available to work with you in the areas of research, writing, speech, and data analysis.
• Peer can also refer to the peer-review process. Articles submitted to peer-reviewed journals must be reviewed by at least one expert in the field. Articles that pass the peer-review process are published in the journal and considered peer-reviewed or refereed.

Learn More:

• Is your source peer-reviewed?
• Finding Sources
• Evaluating Sources