[fos-fer-uh s, fos-fawr-uh s, -fohr-]

adjective Chemistry.

containing trivalent phosphorus.

Origin of phosphorous

First recorded in 1770–80; phosphor- + -ous
Related formsnon·phos·pho·rous, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for phosphorous

Contemporary Examples of phosphorous

Historical Examples of phosphorous

  • They had rubbed some of that phosphorous mineral on their backs.

    The Moon Colony

    William Dixon Bell

  • Does phosphorous ignite spontaneously when held in a warm hand?

  • Because the carbon (charcoal) absorbs oxygen from the air, and conveys it to the phosphorous.

  • The most interesting of them is the oxytrichloride, which corresponds to the phosphorous oxychloride.

  • It was quite dark, but there was a phosphorous glow to the water which made the rolling waves visible.

British Dictionary definitions for phosphorous



of or containing phosphorus in the trivalent state
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

Word Origin and History for phosphorous

1777, "phosphorescent," from phosphorus + -ous. The chemical sense (1794) is immediately from French phosphoreux.

Online Etymology Dictionary, © 2010 Douglas Harper

phosphorous in Medicine


[fŏsfər-əs, fŏs-fôrəs]


Of, relating to, or containing phosphorus, especially with a valence of 3 or a valence lower than that of a comparable phosphoric compound.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.