Do words of uncertain origin make you scowl? If so, glower may put a frown on your face because only part of its history can be validated. The well-established part of its story leads us to Scotland, where glower (or glowren, to use the older Scottish form of the word) has been used since the late Middle Ages. Originally, the word meant simply "to look intently" or "to stare in amazement," but by the late 1700s, glowering stares were being associated with anger instead of astonishment. Beyond that, however, the history of the word is murky. The most we can say is that glower is a distant relative of Middle Low German glūren, which means "to be overcast," and of Middle Dutch gloeren, meaning "to leer."