Definition of "nigra" []

• A negro person (noun)

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• "The result was the spread of a now ubiquitous, lanky hybrid of the American Populus deltoides and European Populus nigra, aka Poplar Hybrid 107."
• "Parkinson's disease, the second most common neurodegenerative disorder in the United States, is characterized by a loss of voluntary movement, the result of the death of neurons in an area of the brain known as the substantia nigra, which is involved in movement control."
• "Parkinson disease results from the death or loss of function of the nervous cells (neurons) in a brain area called substancia nigra, which is involved in the regulation of movement."