Anatomy . either of a pair of bean-shaped organs in the back part of the abdominal cavity that form and excrete urine, regulate fluid and electrolyte balance, and act as endocrine glands.

Zoology . a corresponding organ in other vertebrate animals or an organ of like function in invertebrates.

the meat of an animal's kidney used as food.

constitution or temperament

He was a quiet child, of a different kidney from his boisterous brothers.

kind, sort, or class

He is only at ease with men of his own kidney.