backback2adjectivefurthest from the front: the back doorback teethbackbackbacks1noun1the part of a person or an animal that is between the neck and the bottom: He lay on his back and looked up at the sky. She was standing with her back to me so I couldn't see her face.2the part of something that is behind or furthest from the front: The answers are at the back of the book. Write your address on the back of the cheque. We sat in the back of the car.back to frontwith the back part where the front should be: You've got your sweater on back to front.behind somebody's backwhen somebody is not there, so that they do not know about it: Don't talk about Kate behind her back.backbackbacksbackedbacking4verb (backs, backing, backed)1to move backwards or to make something move backwards: She backed the car out of the garage.2to give help or support to somebody or something: They're backing their school team.back awayto move away backwards: Sally backed away from the big dog.back outto not do something that you promised or agreed to do: You promised you would come with me. You can't back out of it now!back something up1to say or show that something is true: All the evidence backed up what the woman had said.2(computing) to make a copy of information in your computer that you do not want to losebackback3adverb1in or to the place where somebody or something was before: I'll be back (= I will return) at six o'clock.Go back to sleep. We walked to the shops and back.2away from the front: I looked back to see if she was coming. Could everyone move back a bit, please?oppositeforward3as a way of returning or answering something: He paid me the money back. I wrote her a letter, but she didn't write back. I was out when she rang, so I phoned her back.back and forthfrom one place to another and back again, many times: She travels back and forth between London and Glasgow.