Etymology of the Word Radical

Date: 12/28/2001 at 10:31:19
From: Chrissy
Subject: Where do radicals come from?

I have to do a report on where certain words come from. I can't find 
anywhere where the word 'radical' comes from. Is it a Latin word or a 
Greek word or what?

Date: 12/28/2001 at 10:50:38
From: Doctor Sarah
Subject: Re: Where do radicals come from?

Hi Chrissy - thanks for writing to Dr. Math.

From Steven Schwartzman's _The Words of Mathematics_:

radical (noun):

from Latin radix, stem radic- "root," from the Indo-European root 
wrad- "branch, root." An English cognate of radix is root, borrowed 
from Old Norse... In algebra the radical symbol indicates that the nth 
root of a quantity is being taken. The symbol itself is abstracted 
from the first letter of Latin radix. For quite some time the symbol 
was used without a horizontal bar at the top. The current version of 
the symbol is actually a fusion of the stylized letter r and the 
vinculum that was later used when a sum of terms was to have its root 
extracted...

- Doctor Sarah, The Math Forum
  http://mathforum.org/dr.math/