Anything purulent is full of pus. Infected sores are often purulent; that's why Band Aids were invented.
This is a gross-sounding word with a gross meaning: purulent things are full of pus (pussy). A purulent disease is one that generates a lot of pus, and a purulent sore contains or oozes pus. Other liquids that come from our bodies, like blood and urine, are not purulent. A purulent pimple is discharging pus. Also, this word is sometimes used to mean anything disgusting. A story that makes you feel sick could be called a purulent tale.