flame cell - organ of excretion in flatworms

internal organ, viscus - a main organ that is situated inside the body

kidney - 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

apparatus urogenitalis, genitourinary apparatus, genitourinary system, systema urogenitale, urinary apparatus, urinary system, urogenital apparatus, urogenital system - the system that includes all organs involved in reproduction and in the formation and voidance of urine