Here's what rhymes with costineffective.
effective defective affective elective ineffective infective invective respective selective corrective detective directive reflective deflective collective objective perspective subjective connective irrespective convective noneffective protective prospective projective introspective nonobjective retrospective intersubjective Words that almost rhyme with costineffective
festive incentive receptive deceptive inventive restive excessive offensive defensive attentive preventive perceptive pensive unoffensive extensive expensive intensive suggestive digestive obsessive possessive recessive reflexive inoffensive redemptive inattentive retentive disincentive imperceptive unperceptive aggressive impressive successive expressive depressive inexpensive oppressive apprehensive congestive contraceptive preemptive suppressive overattentive comprehensive progressive compressive hypertensive repressive regressive hypotensive unimpressive digressive inexpressive coextensive proprioceptive transgressive counteroffensive overaggressive nonsuccessive antihypertensive retrogressive immunosuppressive