The word identity was first used in English by bishop and historian John Bale in 1545. Back then, he spelled it ydemptyte, but the word quickly evolved to idemptitie, identitie, and by the 1650s the term was widely written identity as we know it. Through Middle French, it all comes from the Latin neuter idem, meaning "the same". Idem is composed of the pronoun is, meaning "he" (and deriving from Proto-Indo-European ey, a third person pronoun), and im, an empathetic marker characteristic of the Proto-Italic language. Usage of the word identity peaked in 2003 and has recently started to slightly decline but today is utilized six times more than it was in 1940, probably due to increased importance placed on our identities in recent years. I was actually pretty surprised there's no connection to the word id, but there you go.
Adam Aleksic, a freshman studying linguistics at Harvard University, has been described as the internet's sixth most famous etymologist. He has disturbing interests in words, vexillology, geography, board games, limericks, and law, and he loves writing about himself in the third person.
The Etymology Nerd