defensible

adjective

1 this is a perfectly defensible attitude:

justifiable, arguable, tenable, defendable, maintainable, sustainable, supportable, plausible, well founded, sound, sensible, reasonable, rational, logical, able to hold water;

acceptable, satisfactory, valid, legitimate, warrantable, permissible, excusable, pardonable, understandable, condonable, vindicable.

▷antonyms indefensible, untenable.

2 a defensible patch of territory:

secure, safe, fortified, fortress-like, protectable, able to be protected, holdable;

invulnerable, impregnable, impenetrable, unattackable, unassailable.

▷antonyms vulnerable.

defensible Oxford Dictionary of English