one-off
adjective [ before noun ]
UK uk/ˌwʌnˈɒf/ us ( US one-shot)
produced or happening only once:
The London store is stocking 12 exclusive, one-off designs.
a one-off opportunity/chance
a one-off cost/payment
one-off
noun [ C ]
ukussomething that happens or that is made or done only once:
The bank's checks indicated the error was a one-off.