1. The first letter of the English alphabet, used to distinguish the first page of a tolio from the second, marked b, or the first page of a book, the first foot note on a printed page, the first of a series of subdivisions, etc., from the following ones, which are marked b, c, d, e, etc. 2. The English indefinite article. This particle is not necessarily a singular term; it is often used in the sense of “any,” and is then applied to more than one individual object.