Just came across this post elsewhere, so it's clearly an issue for many of us.
http://www.kindleboards.com/index.php?topic=31755.0
"Magenta
Status: Arthur Conan Doyle
Re: POLL: Do you use/have turned on "Popular Highlights" on your Kindle?
I can't begin to express how much I HATE this feature. Even more annoying is you have to turn off annotation back-up to prevent your highlights from being shared"
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In any event, I'm trying to figure out how to copy word definitions from the New Oxford American Dictionary that Kindle uses, but no dice. Of course, it's resident on all Macs, so I'll just keep track of words that way, but it would have been nice to have the option to e-mail myself or copy definitions into a growing list! Other dictionaries permit it!
Fair use doctrine permits such copying!