1.Definition: (followed by `to') applying exclusively to a given category or condition or locality
"A species unique to Australia"
2.Definition: highly unusual or rare but not the single instance
"Spoke with a unique accent", "Had unique ability in raising funds", "A frankness unique in literature", "A unique dining experience"
3.Definition: radically distinctive and without equal
"Bach was unique in his handling of counterpoint"
4.Definition: the single one of its kind
"The unique existing example of Donne's handwriting", "A unique copy of an ancient manuscript", "Certain types of problems have unique solutions"