One whose behavior offends or repulses others. I can't believe how poorly he treated that waitress. What a slime ball!

An offensive, detestable, repellent person, especially one who does unscrupulous or immoral things. My last boss was a total slimeball, making all sorts of shady deals to skim a bit of extra profit for herself. That slime ball defrauded his clients for millions of dollars. They ought to lock him up and throw away the key.