To provide facts or evidence that prove or support a claim.
“The report fails to substantiate its claim that the new policy will reduce crime.”
“Further testing is needed to substantiate the initial findings of the pilot study.”
Reading Part 4 often distinguishes between arguments that substantiate their claims with evidence and those that rely only on opinion. Questions frequently test whether you can tell the difference, so pay attention to which side actually substantiates its position with data or examples.
Synonyms: prove, support, verify