Or search: pet, bone, crop, diet, mate, nose, pest, prey, tame, trap, wart, adult, beast, brute, caput
2 Syllables: SU
national, natural, rational
3 Syllables: SUU
affable, animals, arable, cannibal, capitals, casual, comparable, fallible, lateral, laughable, mackerel, marital, Nationale, passable, pastoral
4 Syllables: USUU
bilateral, collateral, compatible, diagonal, grammatical, hexagonal, impassable, implacable, infallible, inflammable, irrational, octagonal, pyramidal, unnatural
5 Syllables: UUSUU
incompatible, multinational, preternatural, supernatural, unilateral

Found 37 words across 4 groupings. Skipped 3 excess words of a similar stem.