one-off

Meanings

1. Occurring once, independent of any pattern; one-time.
2. Special; remarkable; rare; unusual.

1. Something that is done, created, etc. only once, and often quickly, simply, or improvisationally.
2. Something unique and remarkable.

Etymology

From one + off. Probably from foundry work, for which making reusable molds is expensive and expediency makes the rule for molds not to be used only once. A term long used by artists who are printmakers and sculptors to indicate a unique print or casting. If using traditional edition numbering, a one-off would be a "1/1", which is said, "one of one" meaning the first print in an edition of one.