The quality or state of being imprudent; want to caution, circumspection, or a due regard to consequences; indiscretion; inconsideration; rashness; also, an imprudent act; as, he was guilty of an imprudence.

a lack of caution in practical affairs

In the context of FERC rate methodology, a determination that certain of a pipeline’s costs have not been prudently incurred, with the result that the pipeline is prohibited from placing such costs in its rates. See PRUDENT INVESTMENT.