From Longman Dictionary of Contemporary Englishkidneykid‧ney /ˈkɪdni/ ●●○ noun 1 
[countable]HB one of the two organs in your lower back that separate waste products from your blood and make urine a kidney transplant2 [countable, uncountable]DFF one or more of these organs from an animal, used as food steak and kidney pie
[countable]HB one of the two organs in your lower back that separate waste products from your blood and make urine a kidney transplant2 [countable, uncountable]DFF one or more of these organs from an animal, used as food steak and kidney pieExamples from the Corpus
kidney• They are waiting for a kidney donor and time is running out fast.• A kidney, thought to be perfectly healthy was transplanted into a patient on chronic dialysis.• For similar reasons the presence of severe lung disease and chronic kidney disease is a contraindication to disulfiram administration.• Pollution-related illnesses included kidney disease, anaemia and defects in the endocrine system.• Transplant surgeons hope the technique will help to increase live kidney donations and to cut waiting lists.• I wondered if there might be a pickled heart tucked in among all the livers, kidneys, and spleens.• The excretion of mercury by the kidney generally forms the basis for measurement of exposure.• She has been diagnosed with tuberculosis, kidney problems and malnutrition, health workers say.Origin kidney (1300-1400) Perhaps from Old English cwith “abdomen, womb” + æg “egg” 