A Dogmatic (more formerly called an ‘Apostolic’) Constitution is a form of legislation issued by the Pope on a subject such as the Church or the Bible.
An example of a recent Dogmatic Constitution is Dei Verbum (God’s Word) which was released following the second Vatican Council in 1965. In that key teaching document, the Second Vatican Council spelled out in some detail what the Church believes and teaches with regard to divine revelation, primarily as it is contained in the Bible.
Watch the video for a more thorough explanation.