iStarDict En-Kh-Kh is an iPhone's dictionary application that allow you to translate from English to Khmer and from Khmer to Khmer.
Let's see the instruction to install it:
Run Cydia => Manage => Sources => Edit => Add => type: http://iphonekhmer.com => Add source => Done.
After add source already, search the iStarDict En-Kh-Kh then install it.
or you can download iStarDict En-Kh-Kh deb.file here.