PEG is short for polyethylene glycol. It will some times be spelled out on labels. However, in most of the instances I’ve found, it is abbreviated as PEG and then followed by a dash with a number.
Any time you see PEG, it’s part of this same family. In case you were wondering, the number is the molecular weight. Lower weights are better able to penetrate the skin so you’ll see lower numbers in your skincare products.