From BiblePortal Wikipedia

King James Dictionary [1]

Preach, L. proeco, a crier precor.

1. To pronounce a public discourse on a religious subject, or from a subject, or from a text of Scripture. The word is usually applied to such discourses as are formed from a text of Scripture. This is the modern sense of preach. 2. To discourse on the gospel way of salvation and exhort to repentance to discourse on evangelical truths and exhort to a belief of them and acceptance of the terms of salvation. This was the extemporaneous manner of preaching pursued by Christ and his apostles.  Matthew 4;  10 .  Acts 10 . 14 .

Preach, To proclaim to publish in religious discourses.

What ye hear in the ear, that preach ye on the house-tops.  Matthew 10

The Lord hath anointed me to preach good tidings to the meek.  Isaiah 61

1. To inculcate in public discourses.

I have preached righteousness in the great congregations.  Psalms 40

He oft to them preach'd

Conversion and repentance.

To preach Christ or Christ crucified, to announce Christ as the only Savior, and his atonement as the only ground of acceptance with God.  1 Corinthians 1

To preach up, to discourse in favor of.

Can they preach up equality of birth?

Preach, n. A religious discourse. Not used.

Webster's Dictionary [2]

(1): ( v. i.) To proclaim or publish tidings; specifically, to proclaim the gospel; to discourse publicly on a religious subject, or from a text of Scripture; to deliver a sermon.

(2): ( v. t.) To teach or instruct by preaching; to inform by preaching.

(3): ( v. t.) To inculcate in public discourse; to urge with earnestness by public teaching.

(4): ( v.) A religious discourse.

(5): ( v. i.) To give serious advice on morals or religion; to discourse in the manner of a preacher.

(6): ( v. t.) To deliver or pronounce; as, to preach a sermon.

(7): ( v. t.) To proclaim by public discourse; to utter in a sermon or a formal religious harangue.

(8): ( v. t.) To advise or recommend earnestly.