In 1845, the editors of the increasingly Americanizing Webster's Dictionary decided that the word pyjamas was unnecessarily complicated, so they changed it to pajamas, and that's why America spells it differently than the rest of the world. However, the origins are far from these puny Anglo-Saxon languages. When the East India Company ruled India around 1800, its employees started picking up the trend of wearing light, loose pantaloons favored by Muslims and other denizens. These were called pai jamas, which literally meant "leg clothing". Pai comes from the Persian word pae, meaning "leg", which comes from the Proto-Indo-European word ped, with the same meaning. Jamas, meanwhile, comes from jamah, also meaning "clothing", with no offered origin beyond that. This is a really excellent example of how obscure Indian words picked up by European colonists actually come from the same source language as English itself. Very cool!
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