Concise Bible Dictionary:
This is often used in the New Testament for “announcing, or making known,” without the idea of preaching in a formal way, as the word is now understood. When there was persecution in the church at Jerusalem, they were all scattered, except the apostles, and they went everywhere “preaching the word” (Acts 8:1-4).
Solomon in the Ecclesiastes calls himself “the preacher,” and it is said of Noah that he was “a preacher of righteousness.” Paul was appointed a preacher (herald), and it pleased God by “the foolishness of the preaching” to save them that believe. Preaching is still used of God as the means for making known the love of God and the work of Christ.