adverb, adverb taking the 'to' particle
gulp down; drink in big gulps
Mimetic adverb describing the sound or action of drinking large amounts quickly and audibly. Often used with 飲む.
He gulped down the water.
On a hot day, I want to gulp down cold barley tea.
I gulped down the cold barley tea.
I was thirsty, so I gulped down the water.