A more thorough explanation:

manurable (mə-n(y)oor-ə-bəl), adj. [Law French from Old French main “hand”]

Historical term used to describe something that is capable of being held in hand or touched.

• A piece of cloth is manurable because it can be touched and held in hand.
• A rock is also manurable because it can be touched and held in hand.

The examples illustrate that manurable refers to something that can be physically touched or held in hand. Both the cloth and the rock can be touched and held, making them manurable.