Or search: fixture, lodging, fastness, lodgment, lodgement, immovability, immutability, immutableness, immovableness, unalterability, unchangeability, unchangeableness
3 Syllables: SUU
critically, typically, wickedly
4 Syllables: USUU
admittedly, avidity, benignity, cupidity, Euripides, iniquities, iniquity, lucidity, malignity, obliquity, prolixity, stupidity, Thucydides, uncritically, validity
5 Syllables: UUSUU
analytically

Found 19 words across 3 groupings.