Definition of "glas" []

• An element in some place-names of Celtic (mostly Gaelic) origin, signifying ‘dark,’ ‘gray’ (or ‘valley’: see etymology): as, Glasford; Douglas; Strathglass.

The Century Dictionary (Public Domain)

• "Glass "by David Callin, a" meditation on the Welsh word glas [that] manages wonderfully to be intelligent and think-ey and not to lapse into Anglo-Welsh twee. ""
• "However, "glas" can also refer to the color of grass, the color of the sea, and the color of silver, suggesting that, although the distinction between blue and green exists, the dividing point is different between Welsh and English."
• "In Middle Irish and Old Irish, "glas" encompassed green, blue, and some shades of gray."