Here's what rhymes with underactive.
                        
                        
                    
                                interactive  attractive  reactive  inactive  unattractive  proactive  hyperactive  overactive  counteractive  nonactive  refractive  radioactive  extractive  retroactive  vasoactive  psychoactive  nonreactive  putrefactive  nonradioactive  immunoreactive  Words that almost rhyme with underactive
adaptive  captive  massive  passive  contrastive  combative  impassive  maladaptive  expansive