Am I in a Toxic Relationship? What are toxic relationships?

Many people throw around the word toxic. It is definitely a buzz word these days. What is toxic communication? I think about the word toxic as a substance that would make you physically ill or kill you. Now, apply that to communication or relationships. I define it as the way someone communicates in an unhealthy pattern that causes intended or unintended emotional harm to others. It may seem obvious to avoid something that causes you harm. However, I am sure you can think of yourself or others who continuously go back to the same toxic relationship or communication pattern.