preacher (n.)

"one authorized or appointed to discourse publicly on religious subjects," c. 1200, prechour, from Old French preecheor "preacher" (Modern French prêcheur), from Latin praedicatorem (nominative praedicator) "public praiser, eulogist," literally "proclaimer" (see preach). Slang short form preach (n.) is recorded by 1968, American English.