DOOR-KEEPER

Four centuries ago, the word janitor meant "door-keeper", and only later did it have anything to do with cleaning rooms, the connection being that both tasks were encompassed by the role of general caretaker. The word was borrowed in the 1580s from the Latin word ianitor, also "door-keeper", and that comes from the word for "door", ianus​. Ianus is a very interesting word for several reasons: it also held the definitions of "covered passageway", "gate", or "arch", and is the etymon of Janus, the name for the two-faced Roman god of decisions and doorways. It is thought to further derive from the Proto-Indo-European reconstruction hey, meaning "to go". Etymologists aren't a hundred percent sure on that, though, so let's pivot to the synchronic aspect of the word. Janitor has been decreasing in usage since the 1920s, as other terms like custodian became more preferred by the public.