I always assumed puss was white blood cells until someone told me it wasn't. She told me she'd seen white blood cells and it look like a clear yellow liquid (like urine). I still wagered that puss could be white blood cells because the urine looking solution she saw may have been very diluted with water, making it translucide, and that perhaps puss is white blood cells that have captured bacteria or viruses rendering them more opaque (like clear garbage bags that have been filled and are been purged).

 

So what is puss?

It consists in part of dead cells, but also includes proteins and stuff secreted by the white cells. See Wikipedia.

Puss is an affactionate nick-name for a cat as in http://en.wikipedia.org/wiki/Puss_in_Boots'>http://en.wikipedia.org/wiki/Puss_in_Boots

Pus is the stuff that fills up infected wounds.

http://en.wikipedia.org/wiki/Pus