know better (than to (do something))

1. to be wise enough to behave in a more responsible or acceptable way.

It was a stupid thing to do, and I thought she knew better.

You know better than to interrupt when someone else is talking.

Usage notes: sometimes used in the form not know any better:

Doesn't she know any better than to wear jeans to a place like this?

2. to be wise enough to know that you should not believe someone or something.

The guy who was trying to sell us the car said it was in great condition, but I knew better.

• have work cut out for you
• have your back against the wall
• have your back to the wall
• have your beady eye on
• have your beady eye on someone
• have your beady eye on something
• have your cake and eat it
• have your cake and eat it too
• have your day in court
• have your ducks in a row
• have your ear to the ground
• have your end away
• have your eye on
• have your eye on someone
• have your eye on something
• have your feet on the ground
• have your finger on the button
• have your finger on the pulse
• have your fingers in the till
• have your guts for garters
• have your hand in the till
• have your hands full
• have your head in the clouds
• have your head screwed on
• have your head screwed on right