"The review of work products performed by peers during development of the work products to identify defects for removal. The term peer review is used in the CMMI Product Suite instead of the term work product inspection. Essentially, these terms mean the same thing." (Sandy Shrum et al, "CMMI: Guidelines for Process Integration and Product Improvement", 2003)
"A formal review of a complete work product performed by a group to identify defects for removal, and to collect metrics. See also inspection." (Richard D Stutzke, "Estimating Software-Intensive Systems: Projects, Products, and Processes", 2005)
"A system using reviewers who are professional equals; a process used for checking the work performed by one’s equals (peers) to ensure that it meets specific criteria." (Mark S Merkow & Lakshmikanth Raghavan, "Secure and Resilient Software Development", 2010)
"A review of a software work product by colleagues of the producer of the product for the purpose of identifying defects and improvements. Examples are inspection, technical review and walkthrough." (IQBBA, "Standard glossary of terms used in Software Engineering", 2011)
"In relation to internal audit, a form of external assessment that involves a minimum of three organizations assessing each other's internal audit functions using a round-robin approach (A reviews B who reviews C who reviews A)." (Sally-Anne Pitt, "Internal Audit Quality", 2014)