Webster's Revised Unabridged Dictionary · 1913

Sermon

Sermon , noun

[Old English sermoun, sermun, French sermon, from Latin sermo, -onis, a speaking, discourse, probably from serer, sertum, to join, connect; hence, a connected speech. See Series.]

1.
A discourse or address; a talk; a writing; as, the sermons of Chaucer. [Obsolete] — Chaucer
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.
This our life exempt from public haunts Finds tongues in trees, books in the running brooks, Sermons in stones and good in everything. — Shakespeare
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; an exhortation or reproof; a homily; -- often in a depreciatory sense.

Sermon , intransitive verb

[Compare Old French sermoner, French sermonner to lecture one.]

To speak; to discourse; to compose or deliver a sermon. [Obsolete] — Holinshed
What needeth it to sermon of it more? — Chaucer

Sermon , transitive verb

1.
To discourse to or of, as in a sermon. [Obsolete] — Spenser
2.
To tutor; to lecture. [Poetic] — Shakespeare