The Collaborative International Dictionary of English v.0.48:
Arguable \Ar"gu*a*ble\, a. Capable of being argued; admitting of debate. [1913 Webster]WordNet (r) 3.0 (2006):
arguable adj 1: capable of being supported by argument 2: open to argument or debate; "that is a moot question" [syn: arguable, debatable, disputable, moot]