im·pos·si·ble 
(ĭm-pŏsə-bəl)
(ĭm-pŏsə-bəl)adj.
1. Incapable of having existence or of occurring.
2. Not capable of being accomplished: an impossible goal.
3. Unacceptable; intolerable: impossible behavior.
4. Extremely difficult to deal with or tolerate: an impossible child; an impossible situation.
[Middle English, from Old French, from Latin impossibilis : in-, not; see IN-1 + possibilis, possible; see POSSIBLE.]
im·possi·bly adv.