1) For general use 2) Held jointly 
• (a.) Allowed to pasture on public commons. • (a.) Held in common.
Com'mon·a·ble adjective 1. Held in common. 'Forests . . . and other commonable places.' Bacon. 2. Allowed to pasture on public commons. « Commonable beasts are either beasts of the plow, or such as manure the ground. Blackstone. » 
held jointly; for general use; public: commonable lands. · allowed to be pastured on common land: commonable cattle.