untenable (adj.)

• baseless
• defenseless
• empty
• exceptionable
• fatherless
• faulty
• flawed
• friendless
• groundless
• helpless
• idle
• illogical
• implausible
• impossible
• inadmissible
• indefensible
• inexpiable
• insupportable
• intolerable
• motherless
• objectionable
• pregnable
• specious
• unacceptable
• undesirable
• unforgivable
• unfounded
• unjustifiable
• unjustified
• unpardonable
• unprotected
• unreasonable
• unsound
• unsuitable
• unsupportable
• unsupported
• unwarranted
• vain
• vulnerable
• weak