Webster's 1828 Dictionary
IMPROVABLE
a.[See Improve. ] Susceptible of improvement; capable of growing or being made better; that may be advanced in good qualities. We have stock enough, and that too of an improvable nature, that is capable of infinite advancement.
Man is accommodated with moral principles, improvable by the exercise of his faculties.
I have a fine spread of improvable lands.
1. That may be used to advantage, or for the increase of any thing valuable.
The essays of weaker heads afford improvable hints to better.
2. Capable of tillage or cultivation.
A scarcity of improvable lands began to be felt in these colonies.
IMPROVABLENESS
n.Susceptibility of improvement; capableness of being made better, or of being used to advantage.
Webster's 1913 Dictionary
IMPROVABLE
Im *prov "a *ble, a. Etym: [From Improve. ]
1. Capable of being improved; susceptible of improvement; admitting of being made better; capable of cultivation, or of being advanced in good qualities. Man is accommodated with moral principles, improvable by the exercise of his faculties. Sir M. Hale. I have a fine spread of improvable lands. Addison.
2. Capable of being used to advantage; profitable; serviceable; advantageous. The essays of weaker heads afford improvable hints to better. Sir T. Browne.-- Im *pro "a *ble *ness, n. -- Im *prov "a *bly, adv.
The Wordsmith Dictionary