The definition of authenticate is to show or certify that something is not a copy of anything else.(verb)
An expert in antique vases who examines a vase to verify that it is not a replicate or fake is an example of an expert that will authenticate the vase.
See authenticate in Webster's New World College Dictionary
See authenticate in American Heritage Dictionary 4
transitive verb au·then·ti·cat·ed, au·then·ti·cat·ing, au·then·ti·cates
Learn more about authenticate