Something unique is the only one of its kind. A unique specimen, unique to this island, each fingerprint is unique.
Strictly it is an absolute: a thing either is the only one or it is not, which is why very unique and quite unique are objected to. Rather unique and almost unique are more defensible, because they describe how close something comes to being alone in its class. Unique to is a very useful construction meaning found nowhere else. Note that a unique takes a, not an, because the u is pronounced as a y sound.
1adjectiveuniqueThe only one of its kind.
“Every snowflake is supposed to be unique.”
synonyms: one of a kind, singular
2adjectivebelongingBelonging to one person, place or thing alone.
“The bird is unique to that one valley.”
Too few real examples of this word to estimate which sense is commonest.
unique is a quality of being the only one.
Latin unicus means one and only, from unus, one. English borrowed it through French in the seventeenth century, and it was a rare bookish word until the nineteenth, when it became popular and immediately began to loosen.
Latin
unicus
French
unique
English, today
unique
Borrowed from French unique, from Latin unicus.
Etymology from Wiktionary, CC BY-SA