Binding in law or conscience; imposing duty or obligation; requiring performance or forbearance of some act; -- often followed by on or upon; as, obedience is obligatory on a soldier.
- Morally or legally constraining; binding.
- Imposing or recording an obligation: a bill obligatory.
- Of the nature of an obligation; compulsory: Attendance is obligatory. Mathematics is an obligatory course.
- Biology Obligate.