Here is a list of idiomatic expressions beginning with the letter B.

Back seat driver

This expression is used to refer to someone who gives unwanted advice.

Back to square one

When things are back to square one, you have to start all over again.

Back to the drawing board

You have to go back to the drawing board when an attempt to do something fails.

Baker’s dozen

Baker’s dozen means thirteen.

Bark up the wrong tree

To bark up the wrong tree is to put the blame on the wrong person.

Beat a dead horse

To beat a dead horse is to try to revive an issue that has already ended.

Beating around the bush

To beat around the bush is to avoid the main topic.

Bend over backwards

To bend over backwards is to do anything that helps.

Bite off more than one can chew

To bite off more than one can chew is to take on a task that is too difficult for you.

Bite your tongue

To bite your tongue is to avoid talking.

Blood is thicker than water

This expression is used to suggest that family bonds are stronger than any other relationship.

Once in a blue moon

If something happens once in a blue moon, it happens very rarely.

Break a leg

This is a superstitious way to wish someone good luck. Instead of saying ‘good luck’, it says the opposite.

Buy a lemon

To buy a lemon is to buy something that does not work properly.