Swirl: Verb

Definition:  to move in circles or to cause (something) to move in circles

Source:http://www.merriam-webster.com/dictionary/swirl?show=0&t=1387257346

in the essay ” The Dentist” taken from The Things They Carried by Tim O’ Brien the author mentions the word swirl. “There is no clarity, everything swirls.”

now that I know the meaning of this word I understand that he felt like everything was going in circles because he was dizzy.