n. the tetravalent positively-charged phosphorus cation R4P+
the GNU version of the Collaborative International Dictionary of English
n. The hypothetical radical PH4, analogous to ammonium, and regarded as the nucleus of certain derivatives of phosphine.
The Century Dictionary and Cyclopedia
n. A hypothetical compound, analogous to ammonium, formed by the union of four atoms of hydrogen and one of phosphorus (PH4).
Word Usage
"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."