n.1 a spoken or written discourse on a religious or moral subject, esp. a discourse based on a text or passage of Scripture and delivered in a service by way of religious instruction or exhortation.
2 a piece of admonition or reproof, a lecture.
3 a moral reflection suggested by natural objects etc. (sermons in stones).
Phrases and idioms:
Sermon on the Mount the discourse of Christ recorded in Matt. 5-7.
Etymology: ME f. AF sermun, OF sermon f. L sermo -onis discourse, talk