Umass rhymes with:
amass, mass, mass., masse, alas, amass, ass, bass, basse, blass, bras, brass, cas, cass, chasse, class, crass, das, dass, depass, fahs, fass, gas, gass, glas, glass, gras, grass, grasse, harass, hass, impasse, jass, kass, klas, klass, kras, krass, lass, mass, mass., masse, middle-class, morass, nass, pass, plas, plass, plasse, ras, repass, sas, sass, sasse, smartass, surpass, tass, vanasse, vass, yass
Umass sounds like:
umansky, unanimous, unease, uneasy, unesco, ung, ungo, unhinge, unhook, unigesco, union's, unionize, unions, unions', unique, unisex, unisys, unisys', unisys's, unix, unmanage, unmask, unos, unwise, unz