phosfon
/ˈfɒsfɒn/(also phosphon)
noun
An organophosphorus compound used as a growth retardant for plants; 2,4-dichlorobenzyltributylphosphonium chloride, C19H32Cl3P.
Origin
1960s; earliest use found in The Official Gazette. Probably shortened from phosphonium, with change of -ph- to -f- in the spelling.