definitive
adjectiveUK /dɪˈfɪnɪtɪv/
US /dɪˈfɪnɪtɪv/
Something that is the best and most trusted, so it settles a question for good.
The dictionary is the definitive guide to how words are spelled.
RELATED WORDS
OTHER MEANINGS
2. The clearest and most complete of its kind.
She wrote the definitive book on dinosaurs.
3. Able to end doubt or argument completely.
The test gave a definitive answer about the water's safety.
4. Officially decided and not going to change.
The team made a definitive plan for the trip.