Webster's Revised Unabridged Dictionary · 1913

Definitive

Definitive , adjective

[Latin definitivus: compare French définitif.]

1.
Determinate; positive; final; conclusive; unconditional; express.
A strict and definitive truth. — Sir T. Browne
Some definitive... scheme of reconciliation. — Prescott
2.
Limiting; determining; as, a definitive word.
3.
Determined; resolved. [Obsolete] — Shakespeare

Definitive , noun

(Grammar) A word used to define or limit the extent of the signification of a common noun, such as the definite article, and some pronouns.

Definitives... are commonly called by grammarians articles.... They are of two kinds, either those properly and strictly so called, or else pronominal articles, such as this, that, any, other, some, all, no, none, etc.