Something and nothing are semantic place holders for objects. Until you put actual objects in there, they don't mean a thing. — Corvus

That's like saying up and down doesn't mean what every person obviously knows it means, more or less. Sure, it's context dependent. Deep underwater or in space there concepts tend to lose meaning since they're grounded in concepts learned or that otherwise only have meaning in a specific context.

You wouldn't be speaking in any language if you didn't use words assuming each as their widely-used and generally-accepted value.