Softsoap rhymes with:
allotrope, antelope, cantaloupe, envelope, epitope, gastroscope, gyroscope, heliotrope, horoscope, interscope, isentrope, isotope, kaleidoscope, marketscope, microscope, misanthrope, ophthalmoscope, oscilloscope, partenope, periscope, polariscope, stethoscope, telescope, tightrope, worldscope