Large swallows of food or drink, or to swallow something quickly in large amounts, or to make a sound of swallowing.
From Middle English, possibly imitative in origin (imitating the sound of swallowing). The word became common in English by the 1500s.
The word 'gulp' is onomatopoeia—it actually sounds like the thing it describes, which is why it's so fun to say and why it stuck around in English for centuries!
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