TO FALL DOWN

The word occidental, today used to describe things pertaining to countries in the West, was borrowed into English in the fifteenth century in a mostly astrological sense, describing the direction that the sun sets, and it only got applied to civilizations about a hundred years later. Through Old French, the word traces to the Latin word occidens, the noun version of an adjective meaning "setting". That's from the verb occidere, meaning "to fall down", in reference to the motion of the sun. Finally, occidere comes from the prefix ob-, meaning "down" (from Proto-Indo-European opi, "against"), and the root cadere, "to fall down" (from Proto-Indo-European kad, also "fall"). Occidere is also the etymon of the word occasion, through a sense of causation and opportunity. I thought that was interesting!