What does kidney mean?
A kidney is one of the two organs that filter the blood, remove metabolic waste and excess water, and help regulate the body's fluid and mineral balance. The organs also participate in blood-pressure control and hormone production. Although the word is singular, English speakers usually say “kidneys” when referring to the organs collectively or to a person's pair of kidneys. Kidney-related expressions are common in medicine and everyday conversation, including kidney disease, kidney failure, kidney function, and kidney transplant. The word is used both in direct anatomical descriptions and in figurative or compound expressions, although its basic meaning is firmly medical. Its history is somewhat uncertain: the modern word developed through Middle English forms from an Old English ancestor, but the ultimate origin of that ancestor is not securely established.
nounOne of the pair of organs in the abdomen that filter waste and excess water from the blood, regulate the body's fluid and electrolyte balance, and help produce certain hormones. The kidneys are essential for maintaining normal health.
- Either of the two paired organs that filter the blood, remove waste, regulate fluid and electrolyte balance, and contribute to the production of hormones such as erythropoietin and renin.
"Her doctor ordered blood tests to check how well her kidneys were functioning."
"The scan revealed a small cyst on one of her kidneys."
"The medication is prescribed to protect kidney function in patients with diabetes."
The plural is standard when referring to the organs collectively, to a person's two kidneys, or to a condition affecting both organs.
"The imaging scan showed that both kidneys were functioning normally."
Your kidneys are the body's master filters, removing wastes while carefully balancing the salts and water your body needs.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does kidney come from?
The modern form developed from Middle English kidenei, which in turn came from an older Old English form commonly spelled cwidene. The exact ultimate origin of the Old English word is uncertain, and it is not securely connected with the Greek root behind terms such as nephrology.
Related word forms
How kidney is actually used
The term is neutral in general and medical contexts. In anatomy, it is nearly always used in the plural because humans and most animals have two kidneys, although one kidney may be removed or absent.