Tenable

a.

1.

Capable of being held, maintained, or defended, as against an assailant or objector, or against attempts to take or process; as, a tenable fortress, a tenable argument. If you have hitherto concealed his sight, Let it be tenable in your silence still. - Shak. I would be the last man in the world to give up his cause when it was tenable. - Sir W. Scott.

Adj.

1.

tenable - based on sound reasoning or evidence; "a reasonable argument"; "well-founded suspicions" Synonyms: well-founded

OK, acceptable, admissible, agreeable, all right, alright, arguable, believable, colorable, conceivable, condonable, credible, creditable, defendable, defensible, excusable, fiduciary, good enough, imaginable, impregnable, justifiable, maintainable, okay, passable, plausible, possible, reliable, secure, supportable, trustworthy, trusty, unexceptionable, unimpeachable, unobjectionable, unquestionable, viable, vindicable, warrantable, workable, worthy of faith