Synonyms of unfirm

2 Syllables
shabby, shakiest, flimsy, crumbling, shakier, shaky
3 Syllables
aquake, ashake, rickety, tottering, derelict, ramshackle, unsteady, jerry-built, decrepit, unsafe, tumble-down, broken-down
4 Syllables
jellylike
5 Syllables
dilapidated