- 1that cannot live for ever and must die We are all mortal. opposite immortal
- 2(literary) causing death or likely to cause death; very serious a mortal blow/wound to be in mortal danger (figurative) Her reputation suffered a mortal blow as a result of the scandal. compare fatal
- 3[only before noun] (formal) lasting until death synonym deadly mortal enemies They were locked in mortal combat (= a fight that will only end with the death of one of them).
- 4[only before noun] (formal) (of fear, etc.) extreme We lived in mortal dread of him discovering our secret.