dum·my 
(dŭmē)
(dŭmē)n. pl. dum·mies
1. An imitation of a real or original object, intended to be used as a practical substitute.
2.
a. A mannequin used in displaying clothes.
b. A figure of a person or an animal manipulated by a ventriloquist.
c. A stuffed or pasteboard figure used as a target.
d. Football A heavy stuffed cylindrical bag used for blocking and tackling practice.
3. A stupid person; a dolt.
4. A silent or taciturn person.
5.
a. Law A person or entity that is the named party to a transaction but that acts on behalf of another concealed person or entity. Also called nominee, straw person.
b. A person or an agency secretly in the service of another.
6. Printing
a. One of a set of model pages with text and illustrations pasted into place to direct the printer. Also called dummy page.
b. A set of bound blank pages used as a model to show the size and general appearance of a book being published.
7. Games
a. The partner in bridge who exposes his or her hand to be played by the declarer.
b. The hand thus exposed.
8. Computers A character or other piece of information entered into a computer only to meet prescribed conditions, such as word length, and having no effect on operations.
adj.
1. Simulating or replacing something but lacking its function: a dummy pocket; a dummy medication in a study.
2. Serving as a front or cover for another: a dummy corporation.
3. Games Played with a dummy.
4. Computers Entered or provided only to meet prescribed conditions: a dummy variable.
tr.v. dum·mied, dum·my·ing, dum·mies
Printing
Phrasal Verb: Printing
To make a model of (a publication or page).
dummy up Slang
To keep silent; give no information.
[From DUMB.]