1. Expectorated matter; saliva mixed with discharges from the respiratory passages; in ancient and medieval physiology it was believed to cause sluggishness.
2. A substance coughed up from the respiratory tract and usually ejected by mouth; that is, saliva, phlegm, or mucus.
3. Saliva or spittle mixed with mucus or purulent matter, and expectorated in certain diseased states of the lungs, chest, or throat; a mass or quantity of this.
4. Matter spat out or ejected from the lungs, bronchi, and trachea, through the mouth.

Material discharged from the surface of the air passages, throut, or mouth, and removed chiefly by splitting, but in a lesser degree, by swallowing. It may consist of saliva, mucus, or pus, either alone or in any combination. It may also contain microorganisms, fibrin, blood, or its decomposition products, or any inhaled particulate foreign matter.

Sputum consisting chiefly of pus.

Sputum is the mucus and other matter brought up from the lungs, bronchi, and trachea that one may cough up and spit out or swallow.