A demonstrable fact or quality can be shown to be true or to exist. The road safety programme is having a demonstrable effect on road users + demonstrably de·mon·strably demonstrably false statements. able to be shown or proved
necessarily or demonstrably true; "demonstrable truths" capable of being demonstrated or proved; "obvious lies"; "a demonstrable lack of concern for the general welfare"; "practical truth provable to all men"- Walter Bagehot
capable of being demonstrated or proved; "obvious lies"; "a demonstrable lack of concern for the general welfare"; "practical truth provable to all men"- Walter Bagehot