(obsolete) A religious discourse.

(intransitive) To give a sermon.

(transitive) To proclaim by public discourse; to utter in a sermon or a formal religious harangue.

(transitive) To advise or recommend earnestly.

(transitive) To teach or instruct by preaching; to inform by preaching.

(intransitive) To give advice in an offensive or obtrusive manner.

(slang) Expressing strong agreement (as if encouraging somebody to continue speaking).