1.  arguable(s = adj.all) Array - capable of being supported by argument; Array
Derived form verb argue₁

2.  arguable(s = adj.all) debatable, disputable, moot - open to argument or debate; "that is a moot question"

   Capable of being argued; admitting of debate. [1913 Webster]

arguable, adj.
1 that may be argued or reasonably proposed.
2 reasonable; supported by argument.

Derivative:
arguably adv.