Imperious rhymes with:
deleterious, delirious, mysterious, serious, aquarius, curious, deleterious, delirious, demetrius, denarius, dimitrius, dimitrius', furious, glorious, gregarious, hilarious, illustrious, industrious, inglorious, injurious, laborious, lugubrious, marius, meritorious, murias, mysterious, nefarious, notorious, pancreas, penurious, precarious, serious, spurious, stradivarius, tavoulareas, various, vicarious, victorious, vitreous
Imperious sounds like:
imburgia, impairs, impoverish, impoverishes, imprecise, impress, impresses, infers, inverse, invirase