The full form of EUC is excellent used condition
EUC stands for excellent used condition. A seller will use this to indicate that the item for sale has been used, but it＊s still in excellent condition. This usually means it＊s only been worn a few times and still looks new.

Other Meanings of ※EUC§
※EUC§ will primarily stand for ※excellent used condition§ but on rare occasions, it might mean one of these other things:

Extended Unix Code
Everything under control
End-User Certification
Emotions under control
Similar Slang for ※EUC§
You＊re most commonly going to use ※EUC§ in consumer transactions. Therefore, you may also see these other terms.

Used condition 每 the product shows signs of use but still works
Slightly used 每 the item has been used a few times
Almost new 每 hasn＊t been used very much
FC 每 Fine condition 每 shows signs of use but not too much
G 每 Good condition
GU 每 gently used
MNT 每 mint condition
NBW 每 Never been worn
NM 每 Near mint

Conversation Examples
Conversation examples using ※EUC§

Seller837: Old Navy boots. Gray, women＊s size 7. EUC. 2 months old. smoke-free, pet free home. $30 obo
Buyer081: interested. Will you take $25?
Seller837: yes. I＊ll pm pickup dets