soda water

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A solution of water, baking soda, and acid.

from The Century Dictionary.

• noun A drink generally consisting of ordinary water into which carbonic acid has been forced under pressure.
• noun A solution used to cool drills, punches, etc., used in metal-working.

from the GNU version of the Collaborative International Dictionary of English.

• noun originally, a beverage consisting of a weak solution of sodium bicarbonate to which an acid (such as phosphoric acid) has been added to generate carbon dioxide and thus cause effervescence; the term now is also used as a synonym for soda pop. Soda water without flavoring is used as a beverage or as a component of a mixed beverage. It is typically bottled or canned under pressure so that the carbon dioxide and effervescence will be preserved until use.
• noun a beverage containing supersaturated carbon dioxide (carbonic acid) and thus effervescent.
• noun same as soda pop.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Water that has carbon dioxide dissolved in it and has been stored under pressure in a bottle. Usually mixed before drinking with another beverage.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a sweet drink containing carbonated water and flavoring
• noun effervescent beverage artificially charged with carbon dioxide