WordNet sense 1 (unstable by being overloaded at the top):

top-heavy

WordNet sense 2 (inclined to shake as from weakness or defect):

shaky

WordNet sense 3 (liable to lead to sudden change or violence):

volatile

WordNet sense 4 ((used of boats) inclined to heel over easily under sail):

crank, tender

WordNet sense 5 (suffering from severe mental illness):

unsound, mentally ill

WordNet sense 6 (afflicted with or characteristic of mental derangement):

insane

WordNet sense 7 (participating readily in reactions):

reactive

WordNet sense 8 (affording no ease or reassurance):

precarious

WordNet sense 9 (subject to change; variable):

fluid

WordNet sense 10 (such that alteration is possible; having a marked tendency to change):

changeable, changeful