Dum"my (?), a. [See Dumb.] 1. Silent; mute; noiseless; as a dummy engine.

2. Fictitious or sham; feigned; as, a dummy watch.

Dum"my, n.; pl. Dummies (&?;). 1. One who is dumb. H. Smith.

2. A sham package in a shop, or one which does not contain what its exterior indicates.

3. An imitation or copy of something, to be used as a substitute; a model; a lay figure; as, a figure on which clothing is exhibited in shop windows; a blank paper copy used to show the size of the future book, etc.

4. (Drama) One who plays a merely nominal part in any action; a sham character.

5. A thick-witted person; a dolt. [Colloq.]

6. (Railroad) A locomotive with condensing engines, and, hence, without the noise of escaping steam; also, a dummy car.

7. (Card Playing) The fourth or exposed hand when three persons play at a four-handed game of cards.

8. A floating barge connected with a pier. Knight.

• Something constructed with the size and form of a human, to be used in place of a person.
        To understand the effects of the accident, we dropped a dummy from the rooftop.
  
• A deliberately nonfunctional device or tool used in place of a functional one.
        The hammer and drill in the display are dummies.
  
• (Australia & UK) A pacifier.
        The baby wants its dummy.
  
• An unintelligent person.
        Don't be such a dummy!
  
• An bodily gesture meant to fool an opposing player in sport, feints
  
• (linguistics) A word serving only to make a construction grammatical.
        The pronoun "it" in "It's a mystery why this happened" is a dummy.
  
• (complang) An unused parameter or value.
        If flag1 is false, the other parameters are dummies.
  
• A ventriloquist's dummy.