Absolute impudence, out-and-out effrontery. The use of gall, which strictly speaking means the liver’s secretion, or bile, and its extension to bitterness of any kind, dates from about a.d. 1000. In late nineteenth-century America, however, it began to be used in the sense of “nerve” or “brazenness.” Its frequent pairing with unmitigated, meaning “unmodified” or “intense,” occurred in the twentieth century.