অর্থ : Morally or legally constraining or binding.
উদাহরণ :
Attendance is obligatory.
An obligatory contribution.
Possible but not necessary. Left to personal choice.
optionalঅর্থ : Required by obligation or compulsion or convention.
উদাহরণ :
He made all the obligatory apologies.
Obligatory meaning in Bengali (Bangla).