definitive

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

• adjective Serving to define or identify as distinct from others.
• adjective Supplying or being a final settlement or decision; conclusive: synonym: decisive.
• adjective Authoritative and complete.
• adjective Mass produced in indefinite quantities over an indefinite period of time. Used of postage stamps.
• adjective Biology Fully formed or developed, as an organ or structure.
• noun Grammar A word that defines or limits, such as the definite article or a demonstrative pronoun.
• noun A definitive postage stamp.

from The Century Dictionary.

• To make definite.
• Limiting the extent; determinate; positive; express: as, a definitive term.
• Ending; determining; final; conclusive: opposed to conditional, provisional, or interlocutory.
• Specifically— In biology, completely formed; fixed and finished: opposed to primitive or formative: as, the definitive aorta; a definitive anus.
• In logic, applied to a judgment which is accompanied by a full assent of the mind.
• In metaphysics, having position without occupying space.
• noun In grammar, a defining or limiting word, as an article, a demonstrative, or the like.

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

• noun (Gram.) A word used to define or limit the extent of the signification of a common noun, such as the definite article, and some pronouns.
• adjective Determinate; positive; final; conclusive; unconditional; express.
• adjective Limiting; determining.
• adjective obsolete Determined; resolved.

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

• adjective explicitly defined
• adjective conclusive or decisive
• adjective definite, authoritative and complete
• adjective philately general, not issued for commemorative purposes
• noun grammar a word, such as a definite article or demonstrative pronoun, that defines or limits something
• noun philately an ordinary postage stamp that is part of a series of all denominations or is reprinted as needed to meet demand

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

• adjective clearly defined or formulated
• adjective of recognized authority or excellence
• adjective supplying or being a final or conclusive settlement