Acquired immunodeficiency syndrome or Acquired immune deficiency syndrome (AIDS) is a syndrome caused by a virus called HIV.

Acquired means that people are not born with the disease. They get it after being infected with the HIV virus.

Immune or Immuno- talks about the immune system. The immune system is the part of the body that fights off disease.

Deficiency means not enough. An immuno-deficiency is a problem where the immune system is damaged and cannot fight off diseases to keep the body healthy.

Syndrome is a collection of symptoms, or problems in the body. Because the immune system is damaged, and cannot fight off disease, people with AIDS get a collection of symptoms which is referred to as the "Acquired Immunodeficiency Syndrome."