Something that is compatible with something else.
Able to get along well.
Capable of easy interaction.
Consistent; congruous.
A thing without a like; something unequalled or unparallelled; one of a kind.
Of a rare quality, unusual.
Being the only one of its kind; unequaled, unparalleled or unmatched.
Of a feature, such that only one holder has it.
Particular, characteristic.