'Deadly' in the Bible

“Their tongue is a deadly arrow;It speaks deceit;With his mouth one speaks peace to his neighbor,But inwardly he sets an ambush for him.

“They will die of deadly diseases, they will not be lamented or buried; they will be as dung on the surface of the ground and come to an end by sword and famine, and their carcasses will become food for the birds of the sky and for the beasts of the earth.”

Yet You, O Lord, knowAll their deadly designs against me;Do not forgive their iniquityOr blot out their sin from Your sight.But may they be overthrown before You;Deal with them in the time of Your anger!