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.

Example Input: silliness is when a person acts like a fool, or shows a lack of good sense or judgment.
Example Output: silliness

Example Input: spintronics is a kind of electronics that uses the tiny magnetic fields that come from electrons as well as their electric charge.
Example Output: spintronics

Example Input: bob newhart (born september 5, 1929) is an american actor and stand up comedian.
Example Output:
bob newhart