What does "UR" stand for?

[kingo]

I see this often w trades :0

[Pastel-Axle]

UR stands for 'unreleased'; this refers to select pets released only through the December 18th advent box.

[CᴀɴᴅʏNᴜᴛᴍᴇɢ]

Normally on December 18th, everyone adopts three pets and most are old rares/very rares, which is designed to bring pets that aren't traded much back into circulation. Every year, two (or so) new pets are released on the 18th, and these are UR (unreleased [before]) pets.

[kingo]

thank you all!