a.

1. 单一的，单个的；个别的[B]
2. （用于否定句）连一个也（没有）的[B]
   There was not a single person in the house.

   屋子里一个人都没有。

3. 孤单的；单身的；【植】单瓣的
   single parent family

   单亲家庭

   single parent

   单亲

   She remained single till the end of her days.

   她终身未嫁。

4. 单人用的；【英】单程的[B]
   I want a single ticket.

   我要一张单程票。

5. 一个对一个的，单打的
6. 独特的，唯一的
   The child was the single survivor of the air-crash.

   这孩子是那次飞机坠毁事故的唯一幸存者。

7. 专一的

n.[C]

1. 单个；单身者
   singles bar

   单身男女约会的酒吧

2. 单打比赛[P]
   He has won four singles.

   他赢了四场单打赛。

3. 【棒】一垒安打
4. 【口】独唱（或奏）者，独脚戏演员
5. 【英】单程票；单人房
   Would you reserve a single for me?

   请给我预订一间单人房好吗？

6. 【美】一元纸币；【英】一英镑纸币

vt.

1. 选出，挑出[O]
   The boss singled me out for blame.

   老板把我挑出来加以指责。

2. 【棒】以一垒安打得（分）

vi.

1. 【棒】击出一垒安打

adj.

1. only one; not one of several.
   ▸regarded as distinct from others in a group.
   ▸ [with neg.] even one (used for emphasis):

   they didn't receive a single reply.
   ▸designed or suitable for one person.
2. not involved in a stable romantic or sexual relationship.
3. consisting of one part.
   ▸(of a flower) having only one whorl of petals.
4. Brit. (of a ticket) valid for an outward journey only.
5. archaic free from duplicity or deceit:
   a pure and single heart.

n.

1. a single person or thing.
2. a short record with one song on each side.
3. US informal a one-dollar note.
4. Cricket  a hit for one run.
   ▸Baseball  a hit which allows the batter to proceed safely to first base.
5. (singles) (especially in tennis and badminton) a game or competition for individual players.
6. Bell-ringing  a system of change-ringing in which one pair of bells changes places at each round.

v.

1. (single someone/thing out) choose someone or something from a group for special treatment.
2. thin out (seedlings or saplings).
3. reduce (a railway track) to a single line.
4. Baseball  hit a single.
   ▸cause (a run) to be scored by hitting a single.
   ▸advance (a runner) by hitting a single.