distinctive

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Serving to identify; distinguishing or characteristic.
• adjective Distinguished or attractive.
• adjective Linguistics Phonemically relevant and capable of conveying a difference in meaning, as nasalization in the initial sound of mat versus bat.

from The Century Dictionary.

• Marking distinction, difference, or peculiarity; distinguishing from something diverse; characteristic: as, distinctive names or titles; the distinctive characteristics of a species.
• Having the power to distinguish and discern; discerning.
• noun A distinctive mark; specifically, in Hebrew grammar, a distinctive accent. There are 26 of these — 18 disjunctive and 8 conjunctive.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Marking or expressing distinction or difference; distinguishing; characteristic; peculiar.
• adjective obsolete Having the power to distinguish and discern; discriminating.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective that serves to distinguish between things
• adjective that is characteristic or typical of something

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective capable of being classified
• adjective of a feature that helps to distinguish a person or thing