back 1 (b?k)n.1. a. The part of the trunk of the human body along and to the sides of the spine between the neck and the pelvis; the dorsum.b. The analogous dorsal region in other animals.2. The backbone or spine.3. The part or area farthest from the front.4. The part opposite to or behind that adapted for view or use: the back of the hand; wrote on the back of the photograph.5. The reverse side, as of a coin.6. A part that supports or strengthens from the rear: the back of a couch.7. a. The part of a book where the pages are stitched or glued together into the binding.b. The binding itself.8. Sports a. A player who takes a position behind the front line of other players in certain games, such as football and soccer.b. In swimming, backstroke.v. backed, back·ing, backs v.tr.1. To cause to move backward or in a reverse direction: Back the car up and then make the turn.2. To furnish or strengthen with a back or backing.3. a. To provide with financial or material support: Unions backed the pro-labor candidate.b. To lend moral support to, as by corroborating a claim. Often used with up: I’m not comfortable filing a complaint if you won’t back me up.c. To be in favor of; endorse or advocate: backed the reform proposal. See Synonyms at support.4. To provide with musical accompaniment. Often used with up.5. To bet or wager on.6. To adduce evidence in support of; substantiate: backed the argument with facts.7. To form the back or background of: Snowcapped mountains back the village.v.intr.1. To move backward: backed out of the garage.2. To shift to a counterclockwise direction. Used of the wind.adj.1. Located or placed in the rear: Deliveries should be made at the back entrance.2. Distant from a center of activity; remote.3. Of a past date; not current: a back issue of a periodical.4. Being owed or due from an earlier time; in arrears: back pay.5. Being in a backward direction: a back step.6. Linguistics Pronounced with the back of the tongue, as oo in cool. Used of vowels.adv.1. At, to, or toward the rear or back.2. In, to, or toward a former location: went back for the class reunion.3. In, to, or toward a former condition: When the spell broke, the prince turned back into a frog.4. In, to, or toward a past time: This story goes back to the 1920s.5. In reserve or concealment: We kept back some money for emergencies.6. In check or under restraint: Barriers held the crowd back.7. In reply or return: emailed back that he would be late.Phrasal Verbs: back away To withdraw from a position; retreat. back down To withdraw from a position, opinion, or commitment. back off To retreat or draw away. back out1. To withdraw from something before completion.2. To fail to keep a commitment or promise. back up1. To cause to accumulate or undergo accumulation: The accident backed the traffic up for blocks. Traffic backed up in the tunnel.2. Computers To make a backup of (a program or file).Idioms: back and fill1. Nautical To maneuver a vessel in a narrow channel by adjusting the sails so as to let the wind in and out of them in alteration.2. To vacillate in one’s actions or decisions. back to back Consecutively and without interruption: presented three speeches back to back. behind (one’s) back In one’s absence or without one’s knowledge. have got (someone’s) back To be prepared or ready to support or vouch for someone, as in a crisis. have (one’s) back up To be angry or irritated. off (someone’s) back No longer nagging or urging someone to do something. on (someone’s) back Persistently nagging or urging someone to do something.[Middle English bak, from Old English bæc.]back?less adj.back 2 (b?k)n. A shallow vat or tub used chiefly by brewers.[Dutch bak, from French bac, from Old French, boat, from Vulgar Latin *baccus, vessel, probably of Celtic origin.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.back (bæk) n1. (Anatomy) the posterior part of the human body, extending from the neck to the pelvis. 2. (Zoology) the corresponding or upper part of an animal3. (Anatomy) the spinal column4. the part or side of an object opposite the front5. the part or side of anything less often seen or used: the back of a carpet; the back of a knife. 6. the part or side of anything that is furthest from the front or from a spectator: the back of the stage. 7. the convex part of something: the back of a hill; the back of a ship. 8. something that supports, covers, or strengthens the rear of an object9. (Ball Games, other than specified) ball games a. a mainly defensive player behind a forwardb. the position of such a player10. (Printing, Lithography & Bookbinding) the part of a book to which the pages are glued or that joins the covers11. (Mining & Quarrying) mining a. the side of a passage or layer nearest the surfaceb. the earth between that level and the next12. (General Engineering) the upper surface of a joist, rafter, slate, tile, etc, when in position. Compare bed1313. at one’s back behind, esp in support or pursuit14. at the back of one’s mind not in one’s conscious thoughts15. behind one’s back without one’s knowledge; secretly or deceitfully16. break one’s back to overwork or work very hard17. break the back of to complete the greatest or hardest part of (a task)18. on one’s back flat on one’s back incapacitated, esp through illness19. get off someone’s back informal to stop criticizing or pestering someone20. have on one’s back to be burdened with21. on someone’s back informal criticizing or pestering someone22. put one’s back into to devote all one’s strength to (a task)23. put someone’s back up get someone’s back up to annoy someone24. see the back of to be rid of25. back of beyond a. the back of beyond a very remote placeb. Austral in such a place (esp in the phrase out back of beyond)26. turn one’s back on a. to turn away from in anger or contemptb. to refuse to help; abandon27. with one’s back to the wall in a difficult or desperate situationvb (mainly tr) 28. (also intr) to move or cause to move backwards29. to provide support, money, or encouragement for (a person, enterprise, etc)30. (Gambling, except Cards) to bet on the success of: to back a horse. 31. to provide with a back, backing, or lining32. (Music, other) to provide with a music accompaniment: a soloist backed by an orchestra. 33. to provide a background for; be at the back of: mountains back the town. 34. (Commerce) to countersign or endorse35. (Horse Training, Riding & Manège) archaic to mount the back of36. (intr; foll by on or onto) to have the back facing (towards): the house backs onto a river. 37. (Physical Geography) (intr) (of the wind) to change direction in an anticlockwise direction in the northern hemisphere and a clockwise direction in the southern. See veer13a38. (Nautical Terms) nautical to position (a sail) so that the wind presses on its opposite side39. (Nautical Terms) nautical to manoeuvre the sails by alternately filling and emptying them of wind to navigate in a narrow place40. to vacillate in one’s opinionadj (prenominal) 41. situated behind: a back lane. 42. of the past: back issues of a magazine. 43. (Commerce) owing from an earlier date: back rent. 44. chiefly US and Austral and NZ remote: back country. 45. (of a road) not direct46. moving in a backward direction: back current. 47. (Phonetics & Phonology) phonetics of, relating to, or denoting a vowel articulated with the tongue retracted towards the soft palate, as for the vowels in English hard, fall, hot, full, fooladv48. at, to, or towards the rear; away from something considered to be the front; backwards; behind49. in, to, or towards the original starting point, place, or condition: to go back home; put the book back; my headache has come back. 50. in or into the past: to look back on one’s childhood. 51. in reply, repayment, or retaliation: to hit someone back; pay back a debt; to answer back. 52. in check: the dam holds back the water. 53. in concealment; in reserve: to keep something back; to hold back information. 54. back and forth to and fro55. back to front a. in reverseb. in disorder[Old English bæc; related to Old Norse bak, Old Frisian bek, Old High German bah]back (bæk) n (Brewing) a large tub or vat, esp one used by brewers[C17: from Dutch bak tub, cistern, from Old French bac, from Vulgar Latin bacca (unattested) vessel for liquids]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014back1 (bæk) n. 1. the rear part of the human body, from the neck to the end of the spine. 2. the part of the body of animals corresponding to the human back. 3. the rear portion of any part of the body: the back of the head. 4. the part opposite to or farthest from the front; rear: the back of a hall. 5. the part that forms the rear of any object or structure. 6. the part covering the back: the back of a jacket. 7. the spine or backbone: The fall broke his back. 8. any rear part of an object serving to support, protect, etc.: the back of a chair. 9. the side of an object that is less functional, less often seen, etc.: the back of an envelope. 10. the whole body, with reference to clothing: the clothes on one’s back. 11. ability for labor; effort; endurance: to put one’s back to a task. 12. the edge of a book formed where its sections are bound together. 13. (in various sports, as football) a. a player stationed to the rear of front-line play. b. the position so occupied. v.t. 14. to support, as with authority, influence, help, or money: to back a candidate. 15. to bet on: to back a horse in the race. 16. to cause to move backward (often fol. by up): to back a car into a garage. 17. to furnish with a back: to back a book. 18. to lie at the back of; form a back or background for. 19. to provide with an accompaniment: a singer backed by piano and bass. 20. to get upon the back of; mount. 21. to write or print on the back of; endorse; countersign. v.i. 22. to go or move backward (often fol. by up). 23. (of wind) to change direction counterclockwise (opposed to veer). 24. back away, to retreat; withdraw. 25. back down, to abandon an argument or position. 26. back off, a. to move back from something; retreat. b. to back down. 27. back out, to fail to keep an engagement or promise; withdraw. 28. back up, a. to move or cause to move backward. b. to reinforce. c. to support or confirm. d. to bring (a stream of traffic) to a standstill. e. to accumulate or become clogged due to a stoppage. f. to copy (a computer file or program) as a precaution against failure. adj. 29. situated at or in the rear: the back door. 30. far away or removed from the front or main area, position, or rank; remote: back streets. 31. of or belonging to the past: back issues of a magazine. 32. in arrears; overdue: back pay. 33. coming or going back; moving backward: back current. 34. (of a speech sound) articulated with the tongue in the back part of the mouth, as either of the sounds of go. Idioms: 1. back and fill, a. to trim the sails of a boat so that the wind strikes them first on the forward and then on the after side. b. to change one’s opinion or position; vacillate. 2. be (flat) on one’s back, to be ill, helpless, or overcome by circumstances. 3. behind one’s back, without one’s knowledge, esp. treacherously or secretly. 4. break the back of, to conquer the most difficult or resistant part of: to break the back of urban crime. 5. get one’s back up, to become annoyed; take offense. 6. have one’s back to the wall, to be in a difficult or hopeless situation. 7. (in) back of, at the rear of; behind. 8. on someone’s back, Informal. nagging or criticizing someone. [before 1000; Middle English bak, Old English bæc back of the body, c. Old Frisian bek, Old Saxon, Old Norse bak; perhaps You use back with an intransitive verb to say that someone returns to a place where they were before.In conversation, instead of saying that someone will ‘come back’, you often say that they will be back.Be Careful!You never use ‘back’ with the verb return. You do not say, for example, ‘He returned back to his office’. You say ‘He returned to his office’.You use back with a transitive verb to say that someone or something is taken or sent to a place where they were before. Back usually goes after the direct object.When the direct object is a pronoun, back always goes after it.However, when the direct object is a long noun group, or a noun group followed by a relative clause, you put back in front of the noun group.Back can also be used to say that someone or something returns to a state they were in before.Back is also a noun. Your back is the part of your body from your neck to your waist that is on the opposite side to your chest and stomach.The back of an object is the side or part that is towards the rear or farthest from the front.The back of a door is the side which faces into a room or cupboard.The back of a piece of paper is the side which has no writing on, or the side which you look at second.Note that in British English you do not talk about the ‘back side’ of a door or piece of paper. However, in American English, this construction is common.