Generally, a furuncle, a localized, painful swelling of the skin resulting, not from a previous wound, but from infection caused by bacteria that invade hair follicles or sweat or sebaceous glands; in Hebrew, shechinʹ. Beginning with a small red swelling, the boil eventually discharges some pus and, subsequently, its hard center core. At times, a number of boils develop in an affected area. A “carbuncle” is more dangerous than a furuncle, covers a larger area, sometimes produces greater pain, and may be attended by such symptoms as headache, fever, and prostration. It is sometimes fatal.

At the time of Jehovah’s sixth blow against Egypt, the Egyptians and their beasts were plagued by painful “boils with blisters.” (Ex 9:8-11) These may have been severe raised skin eruptions filled with pus, and such blisterlike pustules possibly covered a large area. However, the brief Scriptural description makes definite identification with a specific modern-day disorder impossible.

The Israelites were warned that the consequences of disobedience to God would include his striking them with “the boil of Egypt.” It was further said: “Jehovah will strike you with a malignant boil [Heb., bish·chinʹ raʽ] upon both knees and both legs, from which you will not be able to be healed, from the sole of your foot to the crown of your head.”​—De 28:15, 27, 35.

The Law indicated that a healed boil might be the place of development of a leprous eruption or blotch. In some cases, the symptoms were such that the victim was immediately declared unclean and leprous; in others, a seven-day quarantine was imposed. If it was thereafter found that the condition had not spread, it was identified merely as “the inflammation of the boil” and the priest pronounced the person clean.​—Le 13:18-23.

Satan struck Job “with a malignant boil [Heb., bish·chinʹ raʽ] from the sole of his foot to the crown of his head.” (Job 2:7) The specific medical designation of the disease from which Job suffered is uncertain. In agony, Job scraped himself with a fragment of earthenware. (Job 2:8) His flesh was covered with maggots, his skin formed crusts (Job 7:5), his breath was loathsome (Job 19:17), he was racked with pain, and his skin blackened and dropped off (Job 30:17, 30).

King Hezekiah of Judah was afflicted with a boil and “got sick to the point of dying.” At Isaiah’s suggestion, a cake of pressed dried figs was applied to the boil as a poultice, after which Hezekiah gradually revived. (2Ki 20:1, 7; Isa 38:1, 21) Nonetheless, his recovery was due, not to natural healing alone, but to cure by Jehovah.​—2Ki 20:5.