one-off,只发生一次的; 一次完成的，一次性的事物；绝无仅有

abc

“只发生一次的; 一次完成的，一次性的事物；绝无仅有的事物”， 怎么说英语才地道呢？
one-off
'one-off¹
◙adj [only before noun]  [BrE]
1. happening or done only once, not as part of a regular series
• 只发生一次的; 一次完成的;
【SYN】 one-shot  [AmE] :
»It's yours for a one-off payment of only ￡200.
  只要一次付清 200 英镑，这东西就是你的了。
ˌone-'off²
◙noun [C]  [BrE]
1. something that is done or made only once
• 只做过一次的事; 一次性事物:
»The deal was a one-off.
  这项交易是一次性的。
2.  [informal] someone who is completely different from anyone else
• 与他人完全不同者

one-off
ˌone-'off
adjective
   (BrE) (NAmE 'one-shot) [only before noun]  made or happening only once and not regularly
   一次性的；非经常的:
   a one-off payment
   一次性付款
noun
[sing.]
   (BrE)  a thing that is made or that happens only once and not regularly
   绝无仅有的事物；一次性的事物:
   It was just a one-off; it won't happen again.
   这事绝无仅有；不会再发生了。

one-off
/ˌwʌnˈɑːf/  adj  , always used before a noun
   chiefly Brit   : done or happening only once
   one-off gigs/events
   a one-off cost/payment
  one-off  noun  ,  pl   -offs [  count  ]
   The event is a one-off.

one-off
a ,one-'off (BrE)
■a thing that is made or that happens only once and not regularly 一次性的事物；绝无仅有的事物:
This plate is a one-off produced by Minton in 1898.
这个碟子是明顿陶瓷公司的产品，只在1898年生产过一次。

‘Are they going to do another concert in the church this year?’ ‘I don’t think so. It was just a one-off.’
“他们今年还会在教堂举办音乐会吗？”“不会了，那个音乐会只举办一次。”

■(informal,humorous)a person who is quite unlike other people 与众不同的人:
There’ll never be another Charlie Chaplin. He was a one-off.
再也不会有第二个查理·卓别林了，他是个奇人。

one-off adj.
One-off is used with these nouns: fee, payment, show, special