i Register
In some senses, mandatory is marked as dated, rare. Watch for register when choosing this word.
adj
obligatory; required or commanded by authority.
Attendance at a school is usually mandatory for children.
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
noun
A sign or line that require the path of the disc to be above, below or to one side of it.
A person, organisation or state who receives a mandate; a mandatary.