substantiate
v. C1 Advanced US //səbˈstænʃiˌeɪt// UK //səbstˈænʃɪˌeɪt// sub·stan·ti·ate
v. to prove that something is true or real by providing facts or evidence. You use this when you want to show that a claim has a solid reason behind it.
v. to provide evidence or proof to support a claim, theory, or fact. Transitive — requires a direct object representing the claim or evidence.
The scientist needs to substantiate his theory with new data.
The lawyer asked for documents to substantiate the claim that the company had broken the contract.
While the initial report suggested a significant drop in sales, the final audit failed to substantiate these figures, revealing that the decline was actually a minor seasonal fluctuation.
From Medieval Latin substantiatus (“given substance”), from the verb substantiare, first used 1657.