Term: one-off

one-off (noun) /ˈwʌn.ɒf/

Similar to: unique event; exception; single occurrence; rarity
Definition: something that happens or is made only once and is not intended to be repeated.
Translation: vienreizējs pasākums, izņēmums, unikāls gadījums
Examples: “The concert was a one-off to raise money for charity.”
“We shouldn’t change the whole system based on this one mistake; it was just a one-off.” “
This custom-built car is a one-off; there isn’t another one like it in the world.”