1. something added to complete a thing, supply a deficiency, or reinforce or extend a whole.
2. a part added to a book, document, etc., to supply additional or later information, correct errors, or the like.
3. a part, usually of special character, issued as an additional feature of a newspaper or other periodical.
4. Geom.the quantity by which an angle or an arc falls short of 180° or a semicircle.
1. to complete, add to, or extend by a supplement.
2. to form a supplement or addition to.
3. to supply (a deficiency).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.