unsteady C2+

/ʌnˈstɛdi/ liable to falter or shake; not firm or stable M S

persistency C2+

/pɚˈsɪstənsi/ the quality of persisting; steady continuance or persistence M S

substantive C2+

/ˈsʌbstəntɪv/ having a firm basis in reality; important and meaningful M S

subsistent C2+

/səbˈsɪstənt/ having real or independent existence; self-sustaining M S