Dreamers - literally, as in the margin. People dream dreams for themselves, and go to diviners to ask the explanation of them.
Related Commentaries of Jeremiah 27:9
Jeremiah 27:9
9 Therefore hearken not ye to your prophets, nor to your diviners, nor to your dreamers,c nor to your enchanters, nor to your sorcerers, which speak unto you, saying, Ye shall not serve the king of Babylon: