The medical term 'auer rod' refers to elongated, needle-like structures that appear in leukemia cells. These structures are named after the German pathologist Paul Ehrlich, who first described them in 1879. Although the term 'auer rod' is widely recognized in the medical community, there are other synonyms used to describe these structures. Some of the alternative names used include Auer granules, Auer bodies, and Ehrlich bodies. These terms are often used interchangeably to describe the same feature within leukemia cells. The presence of these structures is an important diagnostic feature of acute myeloid leukemia, a type of cancer that affects the blood and bone marrow.