Real Dictionary

gulp
verb: If you gulp something, you eat or drink it very quickly by swallowing large quantities of it at once.
verb: If you gulp, you swallow air, often making a noise in your throat as you do so, because you are nervous or excited.

gulp in American English
to catch the breath in or as in swallowing a large amount
to swallow hastily, greedily, or in large amounts
intransitive verb: to gasp or choke, as when taking large drafts of a liquid
noun: the act of gulping
transitive verb: to swallow eagerly, or in large drafts or morsels

gulp in British English
noun: the act of gulping
verb: to swallow rapidly, esp in large mouthfuls