in·vin·ci·ble 
(ĭn-vĭnsə-bəl)
(ĭn-vĭnsə-bəl)adj.
Incapable of being overcome or defeated; unconquerable.
[Middle English, from Old French, from Latin invincibilis : in-, not; see IN-1 + vincibilis, conquerable; see VINCIBLE.]
in·vin′ci·bili·ty, in·vinci·ble·ness n.
in·vinci·bly adv.