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: theoxena scissaria is a species of moth.
Example Output: theoxena scissaria

Example Input: lagos state, sometimes referred to as lagos, is a state located in the southwestern part of nigeria.
Example Output: lagos state

Example Input: vitaceae are a family of dicotyledonous flowering plants including the grape and virginia creeper.
Example Output:
vitaceae