improvable

adj

1. Capable of being improved.

   “Therefore, Humanitarians alone devote their present lives to create heavens within themselves and others, and a real paradise upon earth, because they do not waste their time with Pagan delusions, Sceptical doubts, and Atheistical selfishness, but live happily in the present by preparing for themselves and others happier future human lives upon our improveable globe.”

2. Capable of being used to advantage; profitable.
3. (not-comparable)Impossible to prove.