简明英汉词典

 at once
adv.
立刻

美国传统词典[双解]

 once
once
AHD:[w?ns]
D.J.[w(ns]
K.K.[w(ns]
adv.（副词）

(1)

 One time only:
仅仅一次：
once a day.
一天一次

(2)

 At one time in the past; formerly.
过去的某一时间；以前

(3)

 At any time; ever:
从前；曾经：
Once known, his face is never forgotten.
曾经认识，他的面容让人永生难忘

(4)

 By one degree of relationship:
关系相隔一代的：
my first cousin once removed.
我堂亲的孩子
n.（名词）
A single occurrence; one time:
发生一次；一次：
Once will have to do. You can go just this once.
必须去做一次，你只去这一回
conj.（连接词）
As soon as; if ever; when:
一…就；一旦；当…时：
Once he goes, we can clean up.
他一走，我们就能清理
adj.（形容词）
Having been formerly; former:
曾经的；以前的：
the once capital of the nation.
该国以前的首都

习惯用语

 at once

(1)

 All at one time; simultaneously:
立刻；同时：
Everything happened at once. The view of the skyline is at once awesome, grand, and disappointing.
所有的事都一起发生了。天边立刻呈现出令人敬畏的、壮丽的和令人沮丧的景色

(2)

 Immediately; instantly:
立即；马上：
Leave the room at once.
马上离开这个房间

语源

(1)

 Middle English ones
中古英语 ones

(2)

 from on [one]
源自 on [一]

(3)

 from Old English 3n * see oi-no-
源自 古英语 3n *参见 oi-no-

现代英汉词典

 once
[wQns]
adv.

(1)

 一次，一回
I go to see a film once a week.
我每周看一场电影。
"Once a month, he has to collect money from his customers."
"每月一次,他得去向顾客收钱。"
Once a year a race is held for old cars.
每年举行一次旧式小汽车比赛。
"Attention please, I'll repeat the question once more."
请注意我把问题再重复一遍。

(2)

 从前； 曾经
She once knew him.
她以前认识他。
"Once, however, Big Ben failed to give the correct time."
"不过,有一次`大本钟'报错了时间。"
A good editor never once leaves a misprint uncorrected.
一个好编辑决不会放过一个印刷错误。
It once seemed inconceivable to everyone that men should travel to the moon.
"人们一度认为,人飞上月球似乎是不可想象的。"

习惯用语

 all at once
突然, 忽然

at once
马上，立刻；同时
Do it at once.
马上做。
Don't all speak at once!
大家别一块儿说话！

once (and) for all
最后一次
"Once and for all, we can't agree!"
"最后再说一遍,我们不能同意!"

once or twice
几次；一两次

once upon a time
从前
Once upon a time there was a poor old fisherman.
从前有一位贫穷的老渔夫。

词性变化

 once
conj.
一旦；一…就…
Once printed, this dictionary will be very popular!
一旦出版，这本词典将会非常畅销！
Once he arrives we can start.
他一到我们就可以动身。

once
n.
一次
Do it just this once.
只做这一次。
For once he was telling the truth.
他只有这一次说了实话。
"If one once loses self-confidence, he can never expect to be successful."
"一个人一旦失去了自信心,就甭想获得成功。"
Will once be enough?
一次就够了吗?

现代英汉综合大辞典

 once
[wQns]
adv.

(1)

 一次

(2)

 曾经; 从前

(3)

 一旦; 一度

(4)

 [用于否定句]一次也(不); 完全(不)

(5)

 乘以一; (亲属间行辈上)小一辈; (程度上)相差无几
once a year
一年一次
a once powerful nation
曾很强盛的国家
a cousin once removed
堂[表]兄弟[姊妹]的孩子
If the facts once become known, he will be punished.
事实一旦公开, 他就要受到惩罚。
I couldn't once understand what he meant.
我完全不懂他的意思。
Once one is one.
一一得一。

词性变化

 once
conj.
一旦, 每当
Once you begin you must continue.
你一旦开始, 便不可停下来。
n.
一次, 一回
Once is enough for me.
对我来说一次就够了。
adj.
从前的
a once friend
从前的一个朋友

继承用法

 once-forbidden
adj.
一次禁戒的

once-through
n.
强制循环

习惯用语

 all at once
突然; 同时

at once
立刻, 马上; 同时

every once in a while
[美]偶而

for this once (=for once, just for once)
就这一次; 破例一回

if once (=when once)
一旦

more than once
不止一次, 多次

not once
一次也不

once again
再一次

once and again
一再, 再三

once and away
一劳永逸; 限此一次; 断然, 爽快

once for all
一劳永逸; 永久地; 彻底地

once in a while
有时, 间或, 偶而

once more
再一次

once again
再一次

once or twice
一两次; 有时, 偶尔

once over lightly
从头到尾马马虎虎地

once too often
又(多了)一次

美国传统词典

 once
once
AHD:[w?ns]
D.J.[w(ns]
K.K.[w(ns]
adv.

(1)

 One time only:
once a day.

(2)

 At one time in the past; formerly.

(3)

 At any time; ever:
Once known, his face is never forgotten.

(4)

 By one degree of relationship:
my first cousin once removed.
n.
A single occurrence; one time:
Once will have to do. You can go just this once.
conj.
As soon as; if ever; when:
Once he goes, we can clean up.
adj.
Having been formerly; former:
the once capital of the nation.

习惯用语

 at once

(1)

 All at one time; simultaneously:
Everything happened at once. The view of the skyline is at once awesome, grand, and disappointing.

(2)

 Immediately; instantly:
Leave the room at once.

语源

(1)

 Middle English ones

(2)

 from on [one]

(3)

 from Old English 3n * see oi-no-

英汉航海大词典

 at once
prep.立刻,马上

英汉化学大词典

 at once
adv.立即,立刻,同时

英汉经贸大词典

 at once
adv.立即