Morphin rhymes with:
orphan, carstarphen, farfen, orphan, acetaminophen, altenhofen, carstarphen, dalfen, deafen, dextrathoraphan, dolphin, draffen, entoffen, farfen, geffen, giffen, griffen, griffon, hafen, hanifen, hyphen, ibuprofen, kniffen, lafon, ludwigshafen, mcguffin, mcmuffin, muffin, offen, often, orphan, paraffin, siphon, sniffen, soften, steffan, steffen, stephan, stiffen, sutphen, syphon, tamoxifen, toughen, xenophon
Morphin sounds like:
marubeni, marvin, mehrabian, mervin, mervine, mervyn, minervini, moravian, morfin, morphine, morven, murfin