intrinsic

This one is a little Latin hallway trick. Romans built it from intra, “within,” and secus, “alongside” or “following,” so the original image is not a grand philosophical essence but something tucked along the inside edge of a thing. That matters, because intrinsic’s loudest rival, extrinsic, is built with ex- “out of,” as if language itself were pointing inward with one hand and outward with the other. The family resemblance gets even better with intimate, whose Latin ancestor intimus means “inmost,” and with intrinsic’s old neighbor proper, which once meant something like “belonging to itself.” By the time the word arrived in English in the late 1400s, it had lost the hallway and kept the house: what is intrinsic is what belongs to the thing so deeply you can’t peel it off without changing what it is.