Not to be overcome, persuaded, or controlled by any reasonable method; unmanageable; intractable; not capable of being easily dealt with; -- used in a general sense, as applied to a person or thing that is difficult to control or get along with.
not capable of being carried out or put into practice; "refloating the sunken ship proved impracticable because of its fragility"; "a suggested reform that was unfeasible in the prevailing circumstances"