doubtful

From Wiktionary

Adjective[change]

Positive
doubtful

Comparative
more doubtful

Superlative
most doubtful

  1. If something is doubtful it is probably not true.
    The fool made many doubtful claims.
  2. If someone is doubtful they are doubting something or someone.
    The teacher was doubtful of his bad students.