pestilence: a deadly epidemic disease, almost always pictured as a judgment God sends on a people
Deber names a lethal outbreak of disease that sweeps through a population, what older English Bibles call "the pestilence" and we might call a plague or an epidemic. It is not an ordinary illness in one person; it is a mass killer that empties cities and decimates flocks, and in the Bible it is nearly always understood as something God sends or withholds rather than a random misfortune.
The word lives in a fixed company. Again and again it appears as the third member of a grim trio: sword, famine, and pestilence. Together these three sum up the ways a nation dies in war, by the enemy's blade, by the starvation of a siege, and by the disease that breeds in besieged and ruined places. The prophets Jeremiah and Ezekiel use the trio almost as a refrain for the fall of Jerusalem, and the same threat anchors the warnings of the Law and the temple-dedication prayer that asks God to relent when pestilence comes.
Because the meaning holds steady across every passage, this is treated as a single sense. The shadings are matters of setting, not of separate definitions: the same word covers the disease that strikes Egypt's livestock, the outbreak that follows David's census, and the terror that "walks in darkness" in the Ninety-first Psalm. In every case it is the same thing, a deadly contagion in God's hand.