The phrase "a definitive impact" is correct and usable in written English.
It can be used when discussing the clear and certain effects or consequences of an action, event, or decision.
Example: "The new policy had a definitive impact on employee productivity, leading to significant improvements in performance."
Alternatives: "a significant effect" or "a clear influence".
Some of the pieces deliver a definitive impact, while others coalesce and dissolve.
O'Neill, who is an announcer for the YES Network, predicted that Torre would have a definitive impact on a listless Red Sox team.
But it is also true, as many argue, that extended RAF bombing cannot, by itself, have a definitive impact and may even make matters worse.
Variations of elevations have a definitive impact on climate characteristics (Samanta et al. 2012).
Defective telomere elongation appears to have a definitive impact on the true pluripotency and differentiation abilities of iPSCs (Winkler et al., 2013).
In any case, we are aware that a single intervention, albeit cross-cutting, never has a definitive impact on patient prognosis.
While we recommend the continued practice of PMTCT for HIV, and malaria chemoprophylaxis in women of low parity, these recommendations are based primarily on demonstrated benefit for maternal or other fetal/neonatal outcomes, rather than definitive impact on stillbirths or perinatal mortality.
Janie [ 11] also appraised the development and delivery of effective partnerships for children (including reviews of them) and was unable to report substantial robust evidence of definitive impacts.
So the prospective readings are not a definitive measure of impact.
Reforms of this kind often take time to lead to concrete changes on the ground and the current assessment serves as an initial indication of progress and the initial implementation process rather than a definitive evaluation of impact.
The other was a quickly rotating flail system that cleared a definitive path by impacting and flinging the soil away.
