Are Intrepid and Defiant frigates or destroyers?

Do Star Trek's Intrepid and Defiant classes fit frigate or destroyer labels?

The labels depend on the source and naval era. Defiant is heavily armed and sometimes leads other ships, but that is rejected as enough to make it a destroyer leader.

Some sources call Intrepid a frigate, although that classification is disputed. Defiant is treated as a compact, heavily armed warship whose occasional leadership role does not establish it as a destroyer leader. An age-of-sail frigate analogy emphasizes the smaller ship able to cruise independently. A speaker more familiar with steam-and-steel fleets uses frigate for a much smaller vessel. Scout-cruiser and light-cruiser comparisons also appear, but the later replies do not always identify which ship they mean.