If you break down the word sinecure, you can pretty easily discover what it means etymologically. It never was a single word until English (today it means "an easy but well-paid job"); in Latin it was a phrase, beneficium sine cura (somehow the former word got lost in translation), meaning "benefice without care", basically today's definition. Just the sine cura means "without care", reflecting the simplicity of the task. Sine, which we see in sin- ("without"), goes back to Proto-Indo-European swe, "self", and it developed on the sense of "stand alone". Cura you may recognize as being similar to the word cure. This is for good reason; it is the direct etymon of that word; the shared definition is "concern", which makes sense for both venues. This is from Proto-Indo-European kwes, or "to heed". So, if you're truly without caring, in the future you'll call a sinecure "heeding yourself".
Hello! I'm Adam Aleksic, a sophomore studying government and linguistics at Harvard University, where I co-founded the Harvard Undergraduate Linguistics Society. In addition to etymology, I also really enjoy politics, vexillology, geography, board games, conlanging, and law.