topic

(noun) the subject matter of a conversation or discussion. Synonyms: subject, theme. Examples: "He didn't want to discuss that subject." "It was a very sensitive topic." "His letters were always on the theme of love."

(noun) some situation or event that is thought about. Synonyms: subject, issue, matter. Examples: "He kept drifting off the topic." "He had been thinking about the subject for several years." "It is a matter for the police."