universal blood type

Type O blood is the universal blood type and is the only blood type that can be transfused to patients with other blood types.

Patients who have type AB blood are considered universal recipients because they can receive blood or blood products from any other blood type. However, these patients may only donate their blood to patients who have AB blood.
Type O blood (called type zero in some countries) has neither the A or B antigen and therefore, type O negative blood can be given to anyone. Persons with type O negative blood are referred to as “universal donors”.