Corroborate
Etymology
From Latin "corroborare" (to strengthen), from "com-" (intensive) plus "roborare" (to make strong), from "robur" (oak, hardwood, strength) — the same root as robust. To corroborate is to add oaken strength to a claim; the metaphor is of reinforcing timber, not of merely agreeing.
verb · /kuh-ROB-uh-rayt/
To support a claim with additional, independent evidence.
What it names
Use it for the specific act of strengthening a claim from a separate source — a second witness, not a louder repetition of the first.
Example
A second camera corroborated the driver’s account of the crash.
Related idea
Distinguish it from confirm: to confirm can suggest settling a matter, while corroborate specifically means adding independent support that makes a claim stronger without necessarily proving it. Two friends telling the same rehearsed story don’t corroborate it — the independence is the whole point.