Homily
A homily is a commentary that follows a reading of scripture, giving the "public explanation of a sacred doctrine" or text. The works of Origen and John Chrysostom are considered exemplary forms of Christian homily. In Catholic, Anglican, Lutheran, and Eastern Orthodox churches, a homily is usually given during Mass at the end of the Liturgy of the Word.
Many people consider it synonymous with a sermon. The English word homily is derived from the Ancient Greek word ὁμιλία homilia, which means intercourse or interaction with other people. The word is used in 1 Corinthians 15:33.
The related verb is used in Luke 24:14, and in Acts 24:26, both used in the sense of "speaking with". The word later came to have a more technical sense. According to The Catholic Encyclopedia, Origen was the first to distinguish between logos (sermo) and homilia (tractatus).