Walk into the average school cafeteria at lunchtime, and you'll get a good sense of what a din is — loud, confused, continuous, generally unpleasant, and often potentially headache-inducing noise.
Who knew noise pollution was a problem in ancient times? Humans have been experiencing loud, sustained, annoying sounds for centuries, judging by the etymology of the word din. It traces its roots back to Old English dyne or dynn, which had the same meaning as din does today, only with a different pronunciation. Before that, it popped up in Old Norse as dynr and meant to "come rumbling down" — fitting, from the language that gave us Thor, the God of Thunder.