back and forth
Backwards and forwards; in a backward and forward motion.
The chair is rocking back and forth.
The tiger is pacing back and forth in his cage.
The restless lion kept pacing back and forth along the front of its cage.
Grandmother finds it relaxing to sit in her rocking chair and move back and forth.
back away
To act to avoid or lessen one's involvement in something; draw or turn back; retreat.
The townspeople backed away from the building plan when they found out how much it would cost.
back door
Rear of vehicle.
I am watching your back door.
back down
back off
To give up a claim; not follow up a threat.
Bill said he could beat Ted, but when Ted put up his fists Bill backed down.
Harry claimed Joe had taken his book, but backed down when the teacher talked with him.
back in circulation
Socially active once again (said about people); back on the dating circuit after a divorce or a romantic breakup.
Now that Sully is divorced from Jim she is back in circulation.
Once again available to the public (said about types of paper money, rare coins, or other commercially available goods).
In the USA the two-dollar hill was back in circulation for a short time only in the 1950s and 1960s.
back number
Something out of fashion, or out of date.
Among today's young people a waltz like "The Blue Danube" is a back number.
back of
in back of
In or at the rear of; to the back of; behind.
The garage is back of the house.
Our car was in back of theirs at the traffic light.
Being a cause or reason for; causing.
Hard work was back of his success.
The principal tried to find out what was back of the trouble on the bus.
In support or encouragement of; helping, clones will be elected because many powerful men are back of him.
Get in back of your team by cheering them at the game.
back out
To move backwards out of a place or enclosure.
Bob slowly backed his car out of the garage.
The parking lot attendant had to back another car out before he could get to mine.
To withdraw from an activity one has promised to carry out.
Jim tried to back out of the engagement with Jane, but she insisted that they get married.
We were all ready to sign the contracts when one of the parties to the agreement backed out.