adjective, noun, plural -ries.| 1. | authoritatively ordered; obligatory; compulsory: It is mandatory that all students take two years of math. |
| 2. | pertaining to, of the nature of, or containing a command. |
| 3. | Law. permitting no option; not to be disregarded or modified: a mandatory clause. |
| 4. | having received a mandate, as a nation. |
| 5. | mandatary. |