sheḥin

Every verse that uses this word describes the same thing: skin that has gone hot, swollen and raw. It is never a tidy single blemish. In Egypt it erupts on people and animals across the whole country, and it blisters and breaks open (the blisters have their own name in that account, אֲבַעְבֻּעֹת). It hurts badly enough that Pharaoh's own advisers cannot stand in Moses' presence. When it strikes Job, it runs from the soles of his feet to the top of his head.

The same condition shows up in three kinds of setting:

• as a plague sent by God, both on Egypt and in the curses of Deuteronomy, where it is named after Egypt and listed beside other miseries of the skin
• as a private affliction that ruins a life, striking Job, and later King Hezekiah, whose sore Isaiah treats with a pressed cake of figs
• as an ordinary medical condition the priests have to watch, since a boil that heals over can leave a suspicious pale patch behind

That third setting is where the word does its most careful work. A boil by itself does not make anyone unclean. But once it heals, a priest inspects the site, because the defiling skin disease of Leviticus 13 (צָרַעַת) can begin at an old boil. If the hair there has turned white and the patch lies lower than the skin around it, the priest names it that disease; if the patch holds still and does not spread, he calls it nothing more than the scar of the boil and pronounces the person clean. So this word marks the common, harmless case that has to be told apart from the serious one.

Because God strikes with it in Deuteronomy and the accuser strikes Job with it, the word carries more weight in the Bible than a modern reader might guess. It belongs to the language of visible, humiliating, whole-body suffering, the kind that makes a person unfit to be seen.