Definition of "phosphonium" []

• A univalent radical, PH4, derived from phosphine. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "When cotton sleepwear has been treated with flame retardants, this typically is done with tetrakis hydroxymethyl phosphonium THP salts, which are said to be both effective and safe from a general health stand-point."
• "The phosphonium salts are of but little importance."
• "Thus we have phosphonium chloride (PH_ {4} Cl) analogous to ammonium chloride"