Borrowed from Latin exemplum.

exemplum (plural exempla)

1. An example.
2. A story demonstrating a moral point; a parable.
   • 1971, Keith Thomas, Religion and the Decline of Magic, Folio Society, published 2012, page 90:

     In the Middle Ages preachers had enlivened their sermons with exempla – edifying tales of judgements upon sinners and mercies shown to the pious.

• exemplum virtutis