Supplement

Part of speech: noun (n.)

1. That which supplies a deficiency, or meets a want; a store; a supply. [Obs.] Chapman.

2. That which fills up, completes, or makes an addition to, something already organized, arranged, or set apart; specifically, a part added to, or issued as a continuation of, a book or paper, to make good its deficiencies or correct its errors.

3. The number of degrees which, if added to a specified arc, make it 180°; the quantity by which an arc or an angle falls short of 180 degrees, or an arc falls short of a semicircle.

Synonyms: Appendix. Appendix, Supplement. An appendix is that which is appended to something, but is not essential to its completeness; a supplement is that which supplements, or serves to complete or make perfect, that to which it is added.

Part of speech: verb (v.)

To fill up or supply by addition; to add something to. Causes of one kind must be supplemented by bringing to bear upon them a causation of another kind. I. Taylor.