"unique [juːˈniːk]
adj
1. being the only one of a particular type; single; sole
2. without equal or like; unparalleled
3. Informal very remarkable or unusual
4. (Mathematics) Maths
a. leading to only one result the sum of two integers is unique
b. having precisely one value the unique positive square root of 4 is 2
[via French from Latin ūnicus unparalleled, from ūnus one]
uniquely adv
uniqueness 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"
Custom, yes, unique, not so much.