General synonyms:
* Different
* Separate
* Unique
* Individual
* Unmistakable
* Clear
* Obvious
* Discernible
* Notable
* Marked
* Well-defined
More specific synonyms:
* Clear-cut (for boundaries or distinctions)
* Singular (for something that stands out)
* Uncommon (for something unusual or rare)
* Characteristic (for something that defines a person or thing)
* Striking (for something that is impressive or noticeable)
* Definitive (for something that is conclusive or final)
The best synonym to use will depend on the specific meaning you want to convey.