using a neighbors wifi: is it stealing?

[Lemur]

Okay, let me come at this from another angle, since reading another person's newspaper seems like the best analogy so far:

You're at a coffeeshop reading your paper. You leave for a while. Do you, as the owner of that copy of the paper, have any obligation to, say, take your paper with you, or put it behind the counter, or do something to secure your own property? Or should you wait until someone picks it up and looks at it before you storm back in to declare that stealing is wrong?

I think "theft" is an inexact term for this situation, just as it would be not-quite-right for someone reading the paper over your shoulder. If another man sleeps with your girl, likewise, he's done you wrong, but "stealing" isn't quite right. I'm open to a better, more precise term.