Originally Posted by
noirpepper
Is the word 'Yínlián'? Google translate says it means 'Cup'.
I'll try Amex then Discover. This weekend is when I'll plan to put union pay on both of the cards

Yes, that is the proper pinyin (sans tone marks), but if your Chinese isn't good enough to use it in a sentence, it might be best to simply point to the logo on the POS machine.
There is no point putting a union pay sticker on your Amex (or trying to use an Amex in a union pay POS machine).