I learned this from reading Atwood: contrary to popular belief, the phrase mayday has nothing to do with days in the fifth month. Used as a naval and air distress signal, mayday is actually a borrowing from French, where the phrase m'aider meant "help me". The word as we know it was altered to look more Germanic through folk etymology. M' is a contraction of me ("me"), a word we've already explored and one that's pretty ubiquitous in IE languages, going back to the Proto-Indo-European term eme. Aider, the root of the English words aide and aid, unsurprisingly meant "help" or "assist". This is from the Latin verb adutare, which basically goes back to the root iuvere (still "to help", once we eliminate the prefix ad-, meaning "toward"). This in turn is from Proto-Indo-European hewh, which also meant something along the lines of "help". Usage of mayday has increased exponentially since it was introduced in 1923 and search interest for the word is highest in Singapore, for some reason.
Adam Aleksic has been described as the internet's sixth most famous etymologist. He loves writing about himself in the third person, he's a freshman at Harvard University, and he has disturbing interests in linguistics, vexillology, geography, board games, limericks, and law.
The Etymology Nerd