- in a way that settles a matter and puts an end to debate or speculation:The question, "Do habitable conditions for life exist elsewhere in the galaxy?" has been decisively answered in the affirmative.
- in a firm and resolute way, without wavering:The Executive Office must be able to move quickly and decisively to preserve endangered ecosystems, history, or prehistory on federal land.
- in a clear or definite way; indisputably: She has not only decisively beaten but ended the political career of every candidate who ran against her.
