See topic in Webster's New World College Dictionary
noun
Historical
a class or category of considerations or arguments on which a rhetorician may draw
one such consideration or argument
the subject of a paragraph, essay, speech, etc.
a subject for discussion or conversation
a heading or item in an outline
See topic in American Heritage Dictionary 4
(tŏpˈĭk)
noun
The subject of a speech, essay, thesis, or discourse.
A subject of discussion or conversation.
A subdivision of a theme, thesis, or outline. See Synonyms at subject.
Linguistics A word or phrase in a sentence, usually providing information from previous discourse or shared knowledge, that the rest of the sentence elaborates or comments on. Also called theme.