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.
--------
Question: the diamond cutter is a wrestling finishing move done by the wrestler diamond dallas page.

Answer: diamond cutter


Question: nightmare disorder, also known as "dream anxiety disorder", is a sleep disorder characterized by frequent nightmares.

Answer: nightmare disorder


Question: a concert band is an ensemble for playing the instruments using wind.

Answer:
concert band