Subject (music) - Wikipedia
https://en.wikipedia.org/wiki/Subject_(music)Characteristics. A subject may be perceivable as a complete musical expression in itself, separate from the work in which it is found. In contrast to an idea or motif, a subject is usually a complete phrase or period. The Encyclopédie Fasquelle defines a theme (subject) as "[a]ny element, motif, or small musical piece that has given rise to some variation becomes thereby a theme".
Subjects | Open Library
https://openlibrary.org/subjects02.03.2021 · Subject headings are normally applied to every item within a library's collection and facilitate a user's access to items in the catalog that pertain to similar subject matter." Side note: Interestingly, professional library catalogers are often restricted to a limit of 3 in the number of subjects they may use.
Michigan State University Libraries
catalog.lib.msu.eduSearch Tips: Adjacency: Multiple words are searched together as one phrase. Example: world health organization: Wildcards: Words may be right-hand truncated using an asterisk. '*' for 1-5 characters, '**' for open-ended truncation, '?' to replace a single character anywhere within a word.