changeful

adj

1. (rare)Changing frequently; very susceptible to change

   “When we will tempt the frailty of our powers, presuming on their changeful potency.”

   “So, deprived of one leg, and the strange ship of course being altogether unsupplied with the kindly invention, Ahab now found himself abjectly reduced to a clumsy landsman again; hopelessly eyeing the uncertain changeful height he could hardly hope to attain.”