either of two bean-shaped excretory organs that filter wastes (especially urea) from the blood and excrete them and water in urine
"urine passes out of the kidney through ureters to the bladder"
An organ in the body that filters the blood, producing urine.
"The surgeon removed his damaged kidney because it could no longer filter the blood effectively."
In plain English: A kidney is an organ that filters waste and extra water from your blood to keep you healthy.
"The doctor told him to drink more water because his kidneys were not filtering waste properly."
Usage: Kidneys are vital organs responsible for filtering waste from your bloodstream to produce urine. You will typically encounter this word when discussing anatomy, health conditions like kidney failure, or dietary restrictions such as a low-potassium diet.
A surname.
"The local librarian, Mrs. Kidney, helped me find several old books yesterday."
The word "kidney" comes from Middle English and likely combines an old term for belly with one for kidney. While its exact origins are unclear, the root for kidney traces back through Germanic languages to a common ancestor in Proto-Indo-European meaning "kidney."