Words That Rhyme With "Slackened" :
2 syllables:
bacchant, batten, beckoned, blackened, bracken, chickened, craton, dagen, dragon, fagen, fatten, fattened, fecund, gagen, gatten, Grattan, gratton, happen, happened, jocund, machen, macken, maddened, paten, patent, Paton, patten, Patton, ragen, ratton, reckoned, saddened, sagen, second, secund, sickened, staten, tappan, thickened, waggon, wagon, weakened
3 syllables:
attractant, awakened, combatant, contactant, extractant, infecund, manhattan, mayhappen, Mountbatten, pendragon, reactant, surfactant, unreckoned