verify

(verb) confirm the truth of. Examples: "Please verify that the doors are closed." "Verify a claim."

(verb) check or regulate (a scientific experiment) by conducting a parallel experiment or comparing with another standard. Synonyms: control. Examples: "Are you controlling for the temperature?."

(verb) attach or append a legal verification to (a pleading or petition).

(verb) to declare or affirm solemnly and formally as true. Synonyms: affirm, assert, avow, aver, swan, swear. Examples: "Before god i swear i am innocent."