tenable

Capable of being maintained in argument; rationally defensible.

Capable of being held against assault; defensible.

Capable of enduring or of being tolerated.

Capable of being held, maintained, or defended successfully against an assailant; successfully defensible against attacks or arguments or objections: as, a tenable fortress; a tenable theory.

Held; retained; kept secret or inviolate.

Capable of being held, maintained, or defended, as against an assailant or objector, or against attempts to take or process.

capable of being maintained or justified; well-founded

capable of being defended against assault or attack; defensible

based on sound reasoning or evidence