Wikipedia

Peer review is a generic term for a process of self-regulation by a profession or a process of evaluation involving qualified individuals within the relevant field. Peer review methods are employed to maintain standards, improve performance and provide credibility. In academia the term is often used to denote a prepublication review of academic papers; reviewing an academic paper is often called refereeing. 

Merriam-Webster

a process by which something proposed (as for research or publication) is evaluated by a group of experts in the appropriate field

How CINAHL deals with peer review

CINAHL does record whether or not a publication is peer reviewed.  View the full record of a citation to see the Journal Subset field which contains this information

A useful technique is to speed the process of gathering peer reviewed publications is to select Peer Reviewed in the CINAHL options.  This way all of the search results will already be filtered to show only publications that are peer reviewed.

Most of the journals indexed in PubMed are peer reviewed.  However, unlike CINAHL, there is no way to use PubMed to make this distinction for you.

Here are two options for determining if a journal is peer reviewed.

Option A

Find the journal home page and look for specific wording regarding this.  This can be found on various pages of the journal website such as the About page.

Option B

Use a periodicals (another term for journals) directory such as Ulrichsweb international periodicals directory .  Note: Ulrichsweb uses the term 'refereed' instead of 'peer reviewed.'