[ proh-nef-ros, -ruh s ]
/ proʊˈnɛf rɒs, -rəs /

noun, plural pro·neph·roi [proh-nef-roi] /proʊˈnɛf rɔɪ/, pro·neph·ra [proh-nef-ruh] /proʊˈnɛf rə/. Embryology.

one of the three embryonic excretory organs of vertebrates, which becomes the functional kidney of certain primitive fishes.

Origin of pronephros

1875–80; < New Latin < Greek pro- pro-2 + nephrós kidney

Related forms

pro·neph·ric [proh-nef-rik] /proʊˈnɛf rɪk/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for pronephros

British Dictionary definitions for pronephros


/ (prəʊˈnɛfrɒs) /

noun plural -roi (-rɔɪ) or -ra (-rə)

the first-formed anterior part of the embryonic kidney in vertebrates, which remains functional in the larvae of the lower vertebratesSee also mesonephros, metanephros

Derived Forms

pronephric, adjective

Word Origin for pronephros

C19: New Latin, from pro- ² + Greek nephros kidney
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for pronephros


[ prō-nĕfrəs, -rŏs′ ]

n. pl. pro•neph•roi (-roi)

A kidneylike organ, being either part of the most anterior pair of three pairs of organs in a vertebrate embryo, usually disappearing early in embryonic development.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.