neci-, nici- (Latin: death, kill, deadly, murderous, destructive).internecine: 
Damaging or injuring participants on both sides of a conflict or struggle. The original meaning of internecine is  "attended by great slaughter". 
 
perniciosiform: 
In medicine, seemingly pernicious; a term applied to a condition which is apparently, but not actually, pernicious or malignant.
 
pernicious: 
1. Causing great harm, destruction, or death.  
2. Wickedness or causing harm; perniciously. pernicious anemia: 
A severe form of anemia, found mostly in older adults, that results from the body's inability to absorb vitamin B-1 
2. Symptoms include weakness, breathing difficulties, and weight loss.  |