One reason it's hard to conclusively decide whether Adderall works as a " smart pill" is because its effects are so diffuse.
I cannot conclusively define the boundaries of a “humanitarian intervention” and neither can anybody else.
With the dozens of witnesses who conclusively identified him as the shooter, there is no defense that sets him free.
1610s, "occurring at the end," from French conclusif, from Late Latin conclusivus, from conclus-, past participle stem of concludere (see conclude). Meaning "definitive, decisive, convincing" (putting an end to debate) is from 1640s. Related: Conclusiveness.