Albert Barnes Commentary Jeremiah 27:9

"But as for you, hearken ye not to your prophets, nor to your diviners, nor to your dreams, nor to your soothsayers, nor to your sorcerers, that speak unto you, saying, Ye shall not serve the king of Babylon:" — Jeremiah 27:9 (ASV)

Dreamers — literally, as in the margin. People dream dreams for themselves, and go to diviners to ask the explanation of them.