subheading

noun

1. Any of the headings under which each of the main divisions of a subject may be subdivided.

   “And puritans give much the same warning in a manner suggesting that though the eating of rich foods is not among the seven deadly sins, it is at least a bona fide subheading under the general category of gluttony.”

   “Most subheadings don’t do much to enhance a document. The whistle-blower’s subheadings do what the best subheadings do: They structure the complaint and provide a clear outline of what the document contains: […]”

2. A heading or caption subordinate to a main headline, heading, or title especially when inserted as a divider between sections (as of a newspaper or periodical article or story or text of a book).