Sermon

(14), n. [Lat. sermo, sermonis, a speaking, discourse, from serere, sertum, to join, connect, i. q. serta oratio, a connected speech, Fr. & Sp. sermon, Pr. sermo, sermon, It. sermone.]

1. A discourse or address; a talk. [Obs.]
2. Specifically, a discourse delivered in public, usually by a clergyman, for the purpose of religious instruction, and grounded on some text or passage of Scripture.

His preaching much, but more his practice, wrought A living sermon of the truths he taught. Dryden. 3. Hence, a serious address; a lecture on one's conduct or duty; a set exhortation or reproof;— often in a deprecatory sense.