NIST uses confabulation for generated content that is false or erroneous, diverges from the input, or contradicts earlier output; “hallucination” and “fabrication” are common informal terms. The error may be a wrong fact, unsupported inference, invented quotation or citation, internally inconsistent answer, or content that is not supported by the supplied evidence.

Confabulation is not defined by tone. A false answer can sound tentative, and a true answer can sound confident. Generated wording, token probabilities, self-reported confidence, factual correctness, evidential support, and calibrated uncertainty are different quantities and must be evaluated separately.