gulp

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

• intransitive verb To swallow greedily or rapidly in large amounts.
• intransitive verb To choke back by or as if by swallowing.
• intransitive verb To choke or gasp, as in swallowing large amounts of liquid.
• intransitive verb To swallow air audibly, as in nervousness.
• noun The act of gulping.
• noun A large amount swallowed at one time.

from The Century Dictionary.

• To swallow eagerly or in large draughts; hence, figuratively (with down), to repress (emotion) as if by swallowing it.
• noun An act of swallowing; a swallow; also, as much as is swallowed at once.

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

• noun The act of taking a large mouthful; a swallow, or as much as is awallowed at once.
• noun colloq. A disgorging.
• transitive verb To swallow eagerly, or in large draughts; to swallow up; to take down at one swallow.
• transitive verb to throw up from the stomach; to disgorge.

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

• noun The usual amount swallowed.
• noun The sound of swallowing.
• noun A sound of swallowing indicating fear.
• verb To swallow.
• verb To react nervously by swallowing.
• interjection Indication of an involuntary fear reaction.

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

• verb to swallow hurriedly or greedily or in one draught
• noun a spasmodic reflex of the throat made as if in swallowing
• verb utter or make a noise, as when swallowing too quickly
• noun a large and hurried swallow