Here's a simpler word that has also aquired a new meaning that isn't in dictionaries.
We all know what 'need' means, it expresses a requirement for something. Thus "I need a drink" indicates that the speaker is thirsty.
However consider these:
"You need to read this book"
"What you need to understand is that ..."
"You need to be quiet folks"
- which is a less aggressive alternative for the command "Be Quiet!"
The emphasis here has shifted to the speaker telling others what the speaker thinks they need. The shift in meaning has in some cases reached the point where in context the other person plainly doesn't want to comply:
"You need to give me all your money right now!"