Douglas Harper's Etymology Dictionary
one-of-a-kind
adjectival phrase attested from 1961.
Wiktionary
one-of-a-kind
alt. A unique example. n. A unique example.
Usage examples of "one-of-a-kind".
But it was still an impractical, misdesigned creature, a one-of-a-kind on a world with 1560 races.
Those who traveled pretty much alone, the one-of-a-kinds and small groups who also had special needs, had it worst of all.
The USS Tullibee, a small one-of-a-kind attack sub, had long carried a reputation for bad luck.