In`de*fen`si*bil"i*ty (?), n. The quality or state of not being
defensible. Walsh.
In`de*fen"si*ble (?), [Pref. in- not + defensible: cf. OF.
indefensible, indefensable.] Not defensible; not capable of being
defended, maintained, vindicated, or justified; unjustifiable;
untenable; as, an indefensible fortress, position, cause, etc.
Men find that something can be said in favor of what, on the very
proposal, they thought utterly indefensible.
Burke.
In`de*fen"si*bly, adv. In an indefensible manner.