EUC can stand for a number of things, because many acronyms are often recycled for different purposes. EUC could stand for emergency unemployment compensation, excellent used condition, extended unix code or end-use certificate.
"Emergency Unemployment Compensation" was a program that offered specially qualified unemployed citizens benefits beyond normal government unemployment benefits. This program was started in 2008, and expired in 2014 without any decision for extension. "Excellent Used Condition" in terms of selling online means that an item has been opened, but is free of blemishes or malfunctions. "Extended Unix Code" is a multibyte encoding system for Japanese, Korean, and Chinese.