noun
: any of a class of synthetic detergents usually consisting essentially of a quaternary ammonium salt (as cetyl-trimethyl-ammonium chloride [C 16 H 33 N(CH 3 ) 3 ] + Cl - ) with 12 to 24 carbon atoms in the organic groups attached to the nitrogen atom in the cation and valuable as a wetting and emulsifying agent in acid or neutral solutions or as a germicide or fungicide — called also invert soap