cough

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To expel air from the lungs suddenly and noisily, often to keep the respiratory passages free of irritating material.
2. v. To make a noise similar to noisy expulsion of air from the lungs: The engine coughed and died.
3. v. To expel by coughing: coughed up phlegm.
4. n. The act of coughing.
5. n. An illness marked by frequent coughing.
6. cough up Slang To hand over or relinquish (money or another possession), often reluctantly.
7. cough up Slang To confess or disclose: When he saw that the police might arrest him, he coughed up the details of what he had seen.

Century Dictionary and Cyclopedia

1. To make a more or less violent effort, accompanied with noise, to expel the air from the respiratory organs, and force out any matter that irritates the air-passages, or renders respiration difficult.
2. To expel from the air-passages by a more or less violent effort with noise and usually with expectoration: followed by up: as, to cough up phlegm.
3. n. An abrupt and more or less violent and noisy expiration, excited by some irritation of the respiratory organs. It is an effort to drive out with the expelled breath secreted or foreign matters accumulated in the air-passages. The violent action of the muscles serving for expiration gives great force to the air, while the contraction of the glottis produces the sound. A cough is partly voluntary and partly involuntary, and, according to its character, is symptomatic of many bronchial, pulmonary, nervous, and other diseases, often of comparatively slight importance.
4. To lay up for; store as in a coffer.

Wiktionary

1. v. To push air from the lungs in a quick, noisy explosion.
2. v. To make a noise like a cough
3. n. A sudden, usually noisy expulsion of air from the lungs, often involuntary.
4. n. A condition that causes one to cough; a tendency to cough.

GNU Webster's 1913

1. v. To expel air, or obstructing or irritating matter, from the lungs or air passages, in a noisy and violent manner.
2. v. To expel from the lungs or air passages by coughing; -- followed by up.
3. v. To bring to a specified state by coughing.
4. n. A sudden, noisy, and violent expulsion of air from the chest, caused by irritation in the air passages, or by the reflex action of nervous or gastric disorder, etc.
5. n. The more or less frequent repetition of coughing, constituting a symptom of disease.

WordNet 3.0

1. v. exhale abruptly, as when one has a chest cold or congestion
2. n. a sudden noisy expulsion of air from the lungs that clears the air passages; a common symptom of upper respiratory infection or bronchitis or pneumonia or tuberculosis