1) Deadliness 2) Fatalness 3) Morbidity 4) Morbidness 5) The quality of being deadly 6) Unwholesomeness 1) Deadliness 
Lethality or deadliness is how capable something is of causing death. Most often it is used when referring to chemical weapons, biological weapons, or their chemical components. The use of this term denotes the ability of these weapons to kill, but also the possibility that they may not kill. Reasons for the lethality of a weapon to be inconsisten...
• (n.) The quality of being lethal; mortality.
A measure of the impact of a toxic chemical on life processes (human, plant, or animal); the speed with which a toxic chemical inflicts death.
The quality or state of being lethal. ... (05 Mar 2000) ... 
Le·thal'i·ty (le*thăl'ĭ*tȳ) noun [ Confer French léthalité .] The quality of being lethal; mortality. 
Type: Term Pronunciation: lē-thal′i-tē Definitions: 1. The quality or state of being lethal.
lethality, lethalness 1. The quality of being deadly. 2. Capable of causing death.