Introduction, n.
Etymology: [L. introductio: cf. F. introduction. See Introduce.]
1. The act of introducing, or bringing to notice.
2. The act of formally making persons known to each other; a presentation or making known of one person to another by name; as, the introduction of one stranger to another.
3. That part of a book or discourse which introduces or leads the way to the main subject, or part; preliminary; matter; preface; proem; exordium.
4. A formal and elaborate preliminary treatise; specifically, a treatise introductory to other treatises, or to a course of study; a guide; as, an introduction to English literature.
Shades of meaning
Fernald has no entry of its own for introduction; he lists it under entrance.
He lists it without comment; the entries above explain its neighbors.