ISBN
n. countablen. Stands for International Standard Book Number — a unique identifier assigned to each edition of a book, used by publishers, booksellers, and libraries to catalogue and order titles.
n. Abbreviation for International Standard Book Number. A 13-digit (formerly 10-digit) numeric commercial book identifier assigned to each separately-issued edition of a book or book-like product. Administered internationally by the International ISBN Agency; encoded in the EAN-13 barcode on the back cover. Distinct from the ISSN, which identifies serial publications.
You can find the book easily if you have its ISBN.
The librarian asked for the ISBN to ensure she ordered the correct edition of the textbook.
While the title and author remain the same, the hardcover and paperback versions of the novel are assigned a different ISBN to distinguish them in the global supply chain.
Often used with the definite article ('the ISBN') or as a modifier ('ISBN number').
the ISBN numberthe ISBNWhile common in speech, 'ISBN number' is technically redundant because the 'N' already stands for 'Number'.