What term describes evidence that strengthens or confirms an assertion?

The term that describes evidence that strengthens or confirms an assertion is corroboration. Corroboration refers to additional evidence or information that supports a claim or testimony, thereby enhancing its credibility. In legal contexts, the presence of corroborative evidence is crucial because it can bolster a party's case, lending weight to their assertions and helping to establish the truthfulness of their argument.

Testimony involves statements made by witnesses under oath and, while important, it stands alone until supported by corroboration. Insinuation refers to an indirect suggestion or hint, which does not provide direct support or confirmation to an assertion. Verification is the process of establishing the truth or accuracy of something, but it does not specifically denote additional evidence that strengthens a claim. Thus, corroboration is the most precise term for evidence that confirms an assertion.