OK here is a public domain English stardict dictionary; start
here and •Download the dictionary file from James Somers at this
link. Then use WinRAR or 7-zip to find the "stardict-dictd-web1913-2.4.2" folder. Copy that folder into koreader/data/dict/
I have 7 dictionaries installed, including "Stardict format, English Wiktionary, English only, v.2015-Jul-20 based on entries from 2015-Jul-02" (
From here)
Luck;
Ken