Webster's Online Dictionary provided the following definition of pus (accessed Feb. 23, 2008):

“Pus is a whitish-yellow or yellow substance that can be found in regions of bacterial infection, including superficial infections, such as pimples, and deeper infections, such as abscesses.

Pus mainly consists of white blood cells and dead bacteria, as well as inflamatory exudate.

When seen in a wound, pus indicates it is infected, and it should be cleaned with an antiseptic.”

Feb. 23, 2008