Collins English-English Dictionary

unique [juː'niːk]

1. 1. adj being the only one of a particular type; single; sole

2. 2. adj without equal or like; unparalleled

3. 3. adj [informal] very remarkable or unusual

4. 4. adj [maths] leading to only one result

   the sum of two integers is unique

5. 5. adj having precisely one value

   the unique positive square root of 4 is 2

6. 6. adj [Etymology] C17: via French from Latin unicus unparalleled, from unus one

7. 7. n [Usage] unique is normally taken to describe an absolute state, i.e. one that cannot be qualified. Thus something is either unique or not unique; it cannot be rather unique or very unique. However, unique is sometimes used informally to mean very remarkable or unusual and this makes it possible to use comparatives or intensifiers with it, although many people object to this use