Acute leukemia is a type of blood and bone marrow cancer characterized by the rapid and abnormal proliferation of specific blood cells (typically white blood cells) in the bone marrow. This swift and uncontrolled multiplication hinders the production of healthy blood cells. The term 'acute' signifies that this type of leukemia can progress rapidly if left untreated, quickly becoming life-threatening.

There are two main types of acute leukemia:
* Acute Myeloid Leukemia (AML)
* Acute Lymphoblastic Leukemia (ALL)

Acute Myeloid Leukemia (AML) may also be referred to by various other names such as 'Acute Myelocytic Leukemia', 'Acute Myelogenous Leukemia', 'Acute Granulocytic Leukemia', or 'Acute Non-Lymphocytic Leukemia'. The word 'myeloid' refers to the type of cell in the bone marrow where the leukemia originates. Most cases of AML develop from immature cells that would normally mature into white blood cells (other than lymphocytes); however, some cases can also arise from other blood-forming progenitor cells.