obligatory
adjective
1. morally or legally constraining or binding
- attendance is obligatory
- an obligatory contribution
Similar word(s): bounden, compulsory, mandatory, required, imposed, indispensable, prerequisite, necessary
2. required by obligation or compulsion or convention
- he made all the obligatory apologies
Similar word(s): necessary
Sentences with obligatory as an adjective:
- an obligatory promise