Indexed repository of peer-reviewed literature (OpenAlex, PubMed, Semantic Scholar, arXiv, Crossref, CORE, SSRN), searched with Boolean operators; citation chaining — following references backward and citing articles forward — is the most reliable way to map a mature field.
An academic database is a searchable collection of scholarly records — bibliographic metadata, abstracts, sometimes full text — assembled by a particular provider and either sold or given away. Scopus, Web of Science, OpenAlex, PubMed and their peers each define their own inclusion criteria, their own subject taxonomies and their own rules about what counts as a journal worth indexing, and those criteria differ enough that the same search run in two of them returns materially different results. Nothing defines the category itself: there is no register of academic databases and no body that certifies one. A citation here would produce a vendor’s description of its own product, presented as though it settled the general question. Coverage is always a choice made by whoever built the database, and that is the fact worth carrying away.
Why this entry carries no source list. This lexicon cites an official primary source wherever one exists, and says so plainly where none does. No body governs this term. There is no standards organisation for it, no register, and no text whose authors could claim to have settled its meaning. Methods literature describes practice and argues about it; a citation to one author would dress a position in a live argument as a rule, which would mislead more than silence does. What follows is the convention as it is actually used, with the disagreements named rather than smoothed over.