saliva

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

• noun The watery mixture of secretions from the salivary and oral mucous glands that lubricates chewed food, moistens the oral walls, and contains ptyalin.

from The Century Dictionary.

• noun In entomology, a neutral alkaline fluid secreted by the salivary glands when these are present, and, in their absence, by the epithelial lining of the esophagus. It has the same property as the saliva of vertebrates in transforming starchy foods into glucose.
• noun Spittle; the mixed secretion of the salivary glands and of the mucous membrane of the mouth, a colorless ropy liquid which normally has an alkaline reaction.

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

• noun (Physiol.) The secretion from the salivary glands.

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

• noun physiology A clear, slightly alkaline liquid secreted into the mouth by the salivary glands and mucous glands, consisting of water, mucin, protein, and enzymes. It moistens the mouth, lubricates ingested food, and begins the breakdown of starches.

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

• noun a clear liquid secreted into the mouth by the salivary glands and mucous glands of the mouth; moistens the mouth and starts the digestion of starches