a bald patch on the head: hair shaved or torn away as a public sign of grief.
This word names a bald patch that is made, not one that grows. When someone died, or when a city fell, mourners cut or pulled the hair from their heads, and the bare scalp announced their grief the way torn clothes, sackcloth, and gashes on the skin did. The verb for the act (קָרַח) stands beside this noun in the phrase older English Bibles render "make baldness," which is simply their way of saying "shave a bald patch."
The law and the prophets pull in opposite directions here. Priests are told not to make this baldness on their heads, and all Israel is told not to make it "between your eyes for the dead," a phrase most take to mean the hair just above the forehead. Yet Isaiah, Jeremiah, Ezekiel, Amos, and Micah reach for the word freely, with no hint of blame. Most scholars read the bans as an attempt to stamp out a funeral custom Israel shared with its neighbours, one bound up with tending or appeasing the dead, while the prophets simply record what people went on doing.
In the prophets the word grows beyond one mourner's head. It becomes a picture of a whole people in ruin: baldness on every head in Amos, arriving on Gaza in Jeremiah, replacing the carefully styled hair of Jerusalem's women in Isaiah. Micah tells the city to make her baldness as wide as the eagle's, a bird whose head looks bare, so that the bald patch spreads until the entire scalp is stripped.