Investigation rhymes with:
litigation, abrogation, allegation, congregation, conjugation, delegation, desegregation, fumigation, interrogation, irrigation, litigation, navigation, negation, obligation, propagation, segregation, surrogation
litigation, abrogation, allegation, congregation, conjugation, delegation, desegregation, fumigation, interrogation, irrigation, litigation, navigation, negation, obligation, propagation, segregation, surrogation