Why was "tantrum" trending last week?


[proh-nef-ros, -ruh s] /proʊˈnɛf rɒs, -rəs/
noun, plural pronephroi
[proh-nef-roi] /proʊˈnɛf rɔɪ/ (Show IPA),
[proh-nef-ruh] /proʊˈnɛf rə/ (Show IPA).
one of the three embryonic excretory organs of vertebrates, which becomes the functional kidney of certain primitive fishes.
1875-80; < New Latin < Greek pro- pro-2 + nephrós kidney
Related forms
[proh-nef-rik] /proʊˈnɛf rɪk/ (Show IPA),
adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
Cite This Source
British Dictionary definitions for pronephric


noun (pl) -roi (-rɔɪ), -ra (-rə)
the first-formed anterior part of the embryonic kidney in vertebrates, which remains functional in the larvae of the lower vertebrates See also mesonephros, metanephros
Derived Forms
pronephric, adjective
Word Origin
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
Cite This Source
pronephric in Medicine

pronephros pro·neph·ros (prō-něf'rəs, -rŏs')
n. pl. pro·neph·roi (-roi) or pro·neph·ra (-rə)
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.
Cite This Source
Encyclopedia Article for pronephric


most primitive of the three vertebrate kidneys, active in the adults of some primitive fish (lampreys and hagfish), the embryos of more advanced fish, and the larvae of amphibians. It is a paired organ consisting of a series of nephrons that filter urine from both the pericardial cavity fluids via openings called nephrostomes and the bloodstream from the glomerulus. Cells of the nephron tubule may secrete nitrogenous wastes into the urine and reabsorb water and nutrients. Urine passes from the nephrons into one of two long tubes, the Wolffian ducts, which run along either side of the body cavity and empty into a bladderlike urogenital sinus.

Learn more about pronephros with a free trial on
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
Cite This Source

Word of the Day

Difficulty index for pronephros

Few English speakers likely know this word

Word Value for pronephric

Scrabble Words With Friends

Nearby words for pronephric