speciality

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

• noun A distinguishing mark or feature.
• noun Special points of consideration; particulars.
• noun Chiefly British A specialty.

from The Century Dictionary.

• noun A special characteristic or attribute; a distinctive feature, property, or quality; a condition or circumstance especially distinguishing a class or an individual.
• noun A special matter or thing; a characteristic or distinctive object, pursuit, diversion, operation, product, or the like; a specialty. See specialty, 6.

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

• noun A particular or peculiar case; a particularity.
• noun (Law) See Specialty, 3.
• noun The special or peculiar mark or characteristic of a person or thing; that for which a person is specially distinguished; an object of special attention; a special occupation or object of attention; a specialty.
• noun An attribute or quality peculiar to a species.

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

• noun chiefly UK That in which one specialises; a chosen expertise or talent.
• noun An attribute or quality peculiar to a species.

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

• noun the special line of work you have adopted as your career
• noun an asset of special worth or utility
• noun a distinguishing trait