Today’s etymology (and hey, we made it through a week!) is glare, and as usual, I was entirely too amused by it.
Glare showed up in the late thirteenth century meaning shine brightly. It’s related to or descended from the Middle Low German glaren, to gleam, and get this, it’s related to glass. I’m not making that up. There’s a thing in linguistics called rhotacization where people pronounce the s/z sound as r, so glaren actually came from the Proto Germanic glasem, the word for glass. You can go even further back to Proto Indo European, where it’s ghel, which also gave us gold and yellow.
TL;DR: Glass gleams which is why glass is glass and gleam is gleam.