When I first got the word Mlechchha in my etymology requests folder, I honestly thought I was being spammed or something. That doesn't look like a word! The double ch just looks absurd to me as an English speaker, but turns out that it is a legitimate name for a dynasty in the Kamarupa region of India that ruled from 650 to 900 CE. More commonly spelled Mleccha and occasionally also taking the form of Maleccha, the middle sound is just kind of a guttural k. Now, etymologizing this word is very tricky. No Vedic texts give any hint as to its origin, and the earliest citation we have of it is in a context pointing out what a weird word it is. In any form, however, it seems pretty clear that Mleccha comes from Sanskrit, meaning "barbarian" for a while, and some think it's so hard to find because it's regionally rooted. Another theory is that the apellation comes from Sanskrit mili, meaning "speech", and that would be from the (non-IE) Dravidian family. Just some possibilities. Interesting word; my thanks to whoever suggested it!
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.