Antonyms of determined :
undetermined, docile, ambitionless, unambitious, unsettled, unexplained, irresolute, amenable, dutiful, pliable, tractable, complaisant, gentle, pliant, undecided, compliant, submissive, wavering, obedient, teachable, yielding, distrustful, doubtful, dubious, mistrustful, skeptical, suspicious, uncertain, unconvinced, unsure, disinclined, indisposed, loath, reluctant, faltering, hesitant, indecisive, unresolved, vacillating, weak-kneed, slackening, softening, impotent, invertebrate, slack, spineless, weak, obliging.
Examples of usage:
Still, I am determined that Miss Waynefleet shall have no fresh cause for anxiety. "The Greater Power", Harold Bindloss W. Herbert Dunton.
Flora Schuyler nodded as though she believed him, but she determined to leave no room for doubt. "The Cattle-Baron's Daughter", Harold Bindloss.
It may be that you are determined never to marry again. "The Eustace Diamonds", Anthony Trollope.