Setting standards is a quality improvement mechanism and an important means for shaping the provision of health and social care services. Standards comprise statements describing a process or outcome of care. Setting standards is a global practice. It would be useful to have an understanding of the underpinning definitions of standards used internationally. Therefore, the aim of this review was to examine definitions of health and social care standards used internationally and identify similarities and differences. A targeted grey literature search of standard-setting bodies' websites and related health legislation was conducted to retrieve explicit definitions of standards. Of 15 standard-setting bodies that were searched, 12 definitions of standards were narratively synthesised. Terms that appeared in two or more of the definitions were extracted. Counts and percentages were calculated for these terms to determine magnitude of use. The commonalities among definitions included 'quality' (n = 6, 50%), 'statements' (n = 5, 42%), 'performance' (n = 5, 42%), and 'measureable' (n = 4, 33%). The less commonly used terms were 'processes' (n = 3, 25%), 'set' (n = 3, 25%), 'evidence based' (n = 2, 17%), 'outcome' (n = 2, 17%), 'safe' (n = 2, 17%), and 'guidance' (n = 2, 17%). Explicit definitions of standards were not retrieved from health legislation documents. Standard-setting bodies develop standards in the context of the health systems in which they are implemented; some are aspirational levels of quality, while others are minimum levels of quality. Researchers, standards developers and policy makers should be cognisant of this when comparing standards between countries.