Definition from Wiktionary, the free dictionary
- Obligatory; required or commanded by authority.
- Attendance at a school is usually mandatory.
- 1999, Ian Stewart, Jack Cohen, Figments of Reality: The Evolution of the Curious Mind, page 276
- This kind of immediate control structure we take to be characteristic of the tribe, and it leads to a rather rigid type of system in which 'every action not mandatory is forbidden'.
- Of, being or relating to a mandate.
- Mandatory Palestine
- (obligatory): optional
Derived terms 
mandatory (plural mandatories)
- mandatory in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913
- mandatory in The Century Dictionary, The Century Co., New York, 1911
- Oxford Advanced Learner's Dictionary
- The Oxford English Dictionary