one-off

American  

adjective

1. done, occurring, or made only once; one-shot.

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noun

1. something occurring, done, or made only once.

one-off British  

noun

1. Also: one-shot. 

   1. something that is carried out or made only once

   2. ( as modifier )

      a one-off job

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Etymology

Origin of one-off

First recorded in 1935–40

Example Sentences

Victory over Mikel Arteta's side was the one that really resonated with Old Trafford bosses, proving that beating City - something United had done periodically under a number of managers - was not a one-off.

From BBC

People who are struggling and rely on heating oil or liquid petroleum gas will be eligible for a one-off payment of £200 if they are part of the Council Tax Reduction Scheme.

From BBC

This happens so infrequently the disease normally appears as random, isolated one-off cases.

From BBC

The Guardian, external reports that talks are at an advanced stage for a one-off event to be held, which could allow 100,000 runners to take part over the weekend.

From BBC

Staff were also offered a one-off $1,000 bonus but this would not be for casual staff.

From BBC