irresolute

Synonyms: changing doubtful doubting faltering fearful fickle fluctuating halfhearted halting hesitant hesitating hotand-cold infirm on-the-fence shaky tentative timid uncertain undecided undetermined unsettled unstable unsteady vacillating waffling wavering weak weak-kneed wimpy wishy-washy wobbly

Antonyms: definite determined obstinate resolute stubborn unyielding willful