Soften rhymes with:
acetaminophen, altenhofen, carstarphen, dalfen, deafen, dextrathoraphan, dolphin, draffen, entoffen, farfen, geffen, giffen, griffen, griffon, hafen, hanifen, hyphen, ibuprofen, kniffen, lafon, ludwigshafen, mcguffin, mcmuffin, morphin, muffin, offen, often, orphan, paraffin, siphon, sniffen, steffan, steffen, stephan, stiffen, sutphen, syphon, tamoxifen, toughen, xenophon
Soften sounds like:
sabatine, sabatini, sabatino, sefton, septima, shipton, skipton, soviet-union, spadoni, spethmann, spoden, sputum