lethal
Cross references: 1. deadly 1. le.thal \'le--th*l\ \le--'thal-*t-e-\ \'le-th-(*-)le-\ aj [L letalis, lethalis, fr. letum death] 1: of, relating to, or causing death 2: capable of causing death - le.thal.i.ty n 2. lethal n 1: an abnormality of genetic origin causing the death of the organism posse ssing it 2: LETHAL GENE