n.

1. 背脊，背部[C]
   Someone patted me on the back.

   有人在我背上轻轻地拍了一下。

2. 后部[the S][（+of）]
   Grandpa and grandma sat in the back of the car.

   爷爷和奶奶坐在汽车后排的座位上。

3. 后面，背面[the S][（+of）]
4. 椅背[the S] [（+of）]
5. （书报等的）末尾[the S][（+of）]
   There is an appendix at the back of the book.

   该书末尾处有一附录。

6. （足球等的）后卫；后卫球员[C][U]

ad.

1. 在原处；回原处
   Joan and I walked back to the college.

   我和琼步行回到学校。

2. 向后；后退地
   Please go back three steps.

   请退后三步。

3. 以前；追溯
   A few years back you could see nothing but barren land there.

   数年前人们在那儿所能看到的只是荒野。

4. 回复；还；往回
5. 止住；延缓

a.[Z]

1. 后面的，后部的
   He sat in the back seat of the car.

   他坐在车子后面的座位上。

2. 拖欠的，到期未付的
3. 过去的；过期的
   I bought some back issues of science magazines yesterday.

   昨天我买了几本过期的科学杂志。

4. 【语】舌根音的
5. 偏僻的
6. 向后的

vt.

1. 使倒退；使后退
   She backed her car out of the garage.

   她从车库倒车出来。

2. 支持；援助；赞助
   A lot of my friends backed my plan.

   许多朋友支持我的计划。

3. （赛马等）下赌注于；打赌
4. 裱褙；给……加衬里[（+with）]
5. 背书（支票等）
   John backed the check immediately.

   约翰立即背书这张支票。

vi.

1. 倒退；后退
   On seeing the dog, she backed away.

   一见到狗，她便向后退去。

2. 【海】（风）逆时针转向

n.

1. the rear surface of the human body from the shoulders to the hips.
   ▸the corresponding upper surface of an animal's body.
   ▸the spine.
   ▸the main structure of a ship's hull or an aircraft's fuselage.
2. the side or part of something away from the spectator or from the direction in which it moves or faces.
   ▸the side or part of an object opposed to the one that is normally seen or used.
   ▸the part of a chair against which the sitter's back rests.
3. a player in a team game who plays in a defensive position behind the forwards.

adv.

1. in the opposite direction from the one that one is facing or travelling towards.
   ▸at a distance away.
   ▸ (also back of) N. Amer. informal behind.
2. so as to return to an earlier or normal position or condition.
3. in or into the past.
4. in return.

v.

1. give material or moral support to.
   ▸bet money on (a person or animal) winning a race or contest.
2. cover the back of (something) for support, protection, or decoration.
3. (especially in popular music) provide musical accompaniment to (a singer or musician).
4. walk or drive backwards.
   ▸(of the wind) change direction anticlockwise around the points of the compass. The opposite of veer¹.
5. (back on/on to) (of a building or other structure) have its back facing or adjacent to.
   ▸lie behind.

adj.

1. of or at the back.
2. in a remote or subsidiary position.
3. from or relating to the past:
   back pay.
4. directed towards the rear or in a reversed course.
5. Phonetics  (of a sound) articulated at the back of the mouth.