A brain disorder refers to any medical condition that affects the brain's normal functioning. There are several synonyms for the phrase "brain disorder," including neurologic disorder, neurological illness, brain disease, nervous system problem, and cognitive dysfunction. These terms focus on different aspects of the disorder, such as the affected tissues or the specific symptoms involved. For instance, the terms "neurological illness" and "nervous system problem" emphasize the anatomical location where the disorder occurs. Whereas, the phrase "cognitive dysfunction" explains the specific symptoms that result from a brain disorder, such as memory loss, attention deficits, or language problems. All of these synonyms are common in medical parlance and are useful for describing conditions affecting the brain.