Some idioms with “back”

Back and forth = from one place to another e.g. We went to hand in our forms and they sent us back and forth from one department to another.
Back-breaking work = exhausting e.g. It took us one month of back-breaking work to complete the proposal.
Back down = give in e.g. After the demonstration, the mayor backed down on his plans to build a parking lot.
Back-fire = go wrong e.g. Their plan to rob a bank back-fired and the police caught them.
Back of beyond = remote e.g. He’s decided to move to the back of beyond, to a village I’ve never heard of.
At the back of one’s mind = remaining in one’s thoughts e.g. I’ve had the band’s new song at the back of my mind the whole day.
Back to the drawing-board / back to square one = return to the beginning e.g. The client wasn’t pleased with our advertisement so we had to go back to the drawing-board.
Back up = support e.g. I’m not worried about my business failing. I have some savings, so I have back up.
Behind one’s back = without one’s knowledge e.g. They went behind my back and ordered a bigger cake for the office party.
Get off somebody’s back = stop harassing e.g. I wish you’d get off my back! I’m going to take the garbage out now!
Have no backbone = lacking courage e.g. He never disagrees with anything during meetings. He has no backbone.
Like the back of a bus = ugly e.g. I would never date him. He looks like the back of a bus!
Like the back of one’s hand = know well e.g. We’ve lived here for 50 years and know the area like the back of our hands.
Put one’s back into = make an effort e.g. Come on everyone. Put your back into it! How are we going to win the race?
See the back of = be finished with e.g. I’m so glad he left the company. I’m happy to see the back of him.
Stab in the back = betrayal e.g. I thought she was my friend but she stabbed me in the back and told everyone my secret.
Take a back seat = not to be directly involved e.g. She’s resigned from the position of Director and is taking a back seat in the running of the company.
You scratch my back and I’ll scratch yours = to return a favour e.g. If you help me win the contract, I will make sure you get a promotion. You scratch my back and I’ll scratch yours.