Not like the Alamo

• Valid
• Like a valid defense
• Logical, as a theory (7)
• Like a good argument
• Like a rational argument
• Like a solid argument
• Capable of being held

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
"capable of being held or maintained," 1570s, from Middle French tenable , from Old French (12c.), from tenir "to hold," from Latin tenere "to hold, keep" (see tenet ).

WordNet Word definitions in WordNet
adj. based on sound reasoning or evidence; "a reasonable argument"; "well-founded suspicions" [syn: well-founded ]

Wikipedia Word definitions in Wikipedia