Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

[EX Q]: regent's canal is a canal in england.
[EX A]: regent's canal

[EX Q]: monosemy is when the words in a language each have only one meaning.
[EX A]: monosemy

[EX Q]: thomas jefferson national accelerator facility (tjnaf), commonly called jefferson lab or jlab, is a u.s. national laboratory in newport news, virginia.
[EX A]:
thomas jefferson national accelerator facility