Required by rule or law; compulsory.
“Please note that wearing safety equipment is mandatory on the construction site.”
“The orientation session is mandatory for all new employees.”
This word appears in policy-related letters describing rules everyone must follow, such as 'attendance is mandatory.' In the blank-fill section, watch for its opposite, 'optional,' as a common distractor when the sentence context requires certainty rather than choice.
Synonyms: compulsory, required, obligatory