[ 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 formspro·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 Formspronephric, 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.