Subject; theme; a category or general area of interest.
"We decided to change the topic from politics to our upcoming vacation plans during dinner."
In plain English: A topic is the main subject that people are talking about or writing on.
"The main topic of our meeting was the upcoming holiday plans."
Usage: Use "topic" to refer to the specific subject matter being discussed in conversation, writing, or study. It is often interchangeable with "theme," though "topic" typically denotes a narrower scope than the broader concept implied by "theme."
topical
"The journalist chose to cover the recent election results because they were a highly topical issue for voters today."
In plain English: A topic adjective is used to describe something that relates to a specific subject or theme.
"The topic discussion was very important for our meeting."
The word "topic" comes from the Latin topica, which was borrowed from Ancient Greek. Originally meaning "pertaining to a place," it entered English with that same sense of something local or situated in a specific spot.