Igneous rhymes with:
acrimonious, aeneas, aerolineas, antonius, bournias, contemporaneous, cyrenius, erroneous, extraneous, felonious, fresenius, harmonious, homogeneous, ignominious, instantaneous, miscellaneous, morphonios, palonius, parsimonious, percutaneous, phineas, plinius, sanctimonious, simultaneous, spontaneous, thelonius, unceremonious, vilnius
Igneous sounds like:
icahn's, icing, icons, ignace, ignacio, ignacio's, ignasiak, ignominious, iguanas, ijames, isensee, isms, isogenic, issing, issuance, issuances, issuing, izansky, izansky's