Englishfor English speakers
mandatory
Adjective
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If something is mandatory, rules or laws say it must be done.
It is mandatory for children to go to school.
verification
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noun
(= confirmation)
additional proof that something that was believed (some fact or hypothesis or theory) is correct
fossils provided further confirmation of the evolutionary theory
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noun
(law) an affidavit attached to a statement confirming the truth of that statement