2 syllables:
beerus, birrus, cheer us, cirrus, cuirass, freerice, hear us, iiris, kriorus, lyris, miris, mirus, near us, pthirus, pyrrhus, seeress, siris, sirus, viris

3 syllables:
anguirus, epirus, jabirus, lampyris, magirus, osyris, pamiris, sotiris, tapirus, thamyris, tomyris, veneris

4 syllables:
menticirrhus, panegyris, perochirus, polycirrus, strato-cirrus

2 syllables:
spirits, maurice, orris, morris, naris, doris, harris, paris, iris, derris, merits, norris, aurous, carrots, ceras, chorus, cyrus, ferrous, gyrus, heiress, horus, larus, laurus, morus, parus, pirates, porous, purace, purus, pyrus, sorus, starets, taurus, terrace, torus, virus

3 syllables:
slow loris, herb paris, osiris, clitoris, acorus, ailurus, arcturus, atherurus, baccharis, belarus, bos taurus, botaurus, centaurus, corchorus, desirous, dutch iris, dwarf iris, embarrass, greek chorus, hesperis, high spirits, honduras, in chorus, lathyrus, leonurus, low spirits, luvarus, lyrurus, micrurus, necturus, paliurus, papyrus, petaurus, pipturus, plant virus, polaris, psithyrus, pylorus, quakeress, sciurus, seiurus, silurus, slow virus, thesaurus, triturus

4 syllables:
allosaurus, ameiurus, ankylosaurus, ardent spirits, automeris, barosaurus, bearded iris, brontosaurus, bulbous iris, byelarus, callisaurus, camptosorus, cistothorus, conilurus, cyclosorus, dasyurus, dinoceras, dipsosaurus, disembarrass, echovirus, english iris, genus iris, german iris, hadrosaurus, herpes virus, hydrocharis, hydrochoerus, in good spirits, in high spirits, in low spirits, myxovirus, neutral spirits, nigroporus, ocyurus, ophisaurus, palinurus, parvovirus, persian iris, phylloporus, plesiosaurus, pleurosorus, polyborus, polyporus, raphicerus, reovirus, retrovirus, rhabdovirus, sceloporus, seismosaurus, smallpox virus, spanish iris, stegosaurus, sternotherus, stinking iris, tetrapturus, thryothorus, tumor virus, undesirous, urosaurus, vernal iris, xenosaurus, yellow iris

5 syllables:
plaster of paris, actinomeris, alepisaurus, alopecurus, animal virus, apatosaurus, british honduras, ceratosaurus, chlamydosaurus, corythosaurus, dalmatian iris, deinocheirus, ebola virus, edaphosaurus, edmontosaurus, eleocharis, florentine iris, herrerasaurus, ichthyosaurus, japanese iris, megalosaurus, oligoporus, paradoxurus, pisanosaurus, poliovirus, psittacosaurus, staurikosaurus, styracosaurus, titanosaurus, tyrannosaurus, wound tumor virus

6 syllables:
genus brontosaurus, genus stegosaurus, herpes simplex virus, herpes zoster virus, judgement on the merits, judgment on the merits, orthomyxovirus, paramyxovirus, tamiasciurus

7 syllables:
cytomegalovirus, genus tyrannosaurus, hepatitis a virus, pachycephalosaurus

8 syllables:
human papilloma virus, tobacco mosaic virus

11 syllables:
human immunodeficiency virus