1540s, "sullen, moody, frowning," from Middle English gloumen (v.) "become dark" (c.1300), later gloumben "look gloomy or sullen" (late 14c.); see gloom. Or from or influenced by Low German glum "gloomy, troubled, turbid." In English the word was also formerly a noun meaning "a sullen look" (1520s). An 18c. extended or colloquial form glump led to the expression the glumps "a fit of sulkiness." Glunch (1719) was a Scottish variant. Related: Glumly; glumness.