immune system

/ɪˈmjun ˈsɪstɪm/

/ɪˈmjun ˈsɪstɪm/

Other forms: immune systems

The cells and proteins in your body that work to defend you against disease are your immune system. When you feel sick, it's your immune system that attempts to fight your cold.

When you're exposed to germs, you depend on your immune system to protect you from getting sick. It's a complex network of defenses, ranging from coughing (one of the many ways your body fights against anything harmful entering it) to white blood cells, which do battle against foreign substances and pathogens. Vaccines work by spurring your immune system into action, protecting your body against specific viruses.

Definitions of immune system

1. noun

   a system (including the thymus and bone marrow and lymphoid tissues) that protects the body from foreign substances and pathogenic organisms by producing the immune response
   type of:

   system

   a group of physiologically or anatomically related organs or parts