DictEm is an RFC 2229 dict client for Emacs. Get it from the author at
On a Debian system see DebianPackage:dictem. And read more at freshmeat
On PkgSrc (packaging system for NetBSD, DragonFlyBSD and many others) it is packaged in textproc/dictem.
The package uses the command-line
dict program (http://sourceforge.net/projects/dict).