topic in WordNet English dictionary

1. some situation or event that is thought about
   "he kept drifting off the topic"; "he had been thinking about the subject for several years"; "it is a matter for the police"
   topic  subject  issue  matter 
   
2. the subject matter of a conversation or discussion
   "he didn't want to discuss that subject"; "it was a very sensitive topic"; "his letters were always on the theme of love"
   subject  topic  theme