I. ˈsəb+ˌ- noun
Etymology: sub- + head
1. : any of the heads under which each of the main divisions of a subject may be subdivided
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)
II. | ̷ ̷| ̷ ̷ transitive verb
: to provide (as a manuscript or discourse) with subheads : introduce by a subhead