unique

Radically distinctive and without equal.

“Bach was unique in his handling of counterpoint”

The single one of its kind.

“the unique existing example of Donne's handwriting”

“a unique copy of an ancient manuscript”

(followed by `to') applying exclusively to a given category or condition or locality.

“a species unique to Australia”

Highly unusual or rare but not the single instance.

“spoke with a unique accent”

“had unique ability in raising funds”