refutable (adj.)

• arguable
• confutable
• conjectural
• contestable
• controversial
• controvertible
• debatable
• defeasible
• deniable
• disputable
• doubtable
• doubtful
• dubious
• dubitable
• iffy
• mistakable
• moot
• problematic
• questionable
• speculative
• suppositional
• suspect
• suspicious