com·pul·so·ry /kəm-'pəl-sə-rē/ adj1: required or compelled by law: mandatory obligatorycompulsory insurance; specif: required to be brought or asserted in a pleading because of having arisen from the transaction or occurrence that is the subject of litigationa compulsory counterclaim2: using compulsion: compellingcompulsory measurescom·pul·so·ri·ly /-sə-rə-lē/ adv
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.
against one's will, authoritative, binding, coactive, coercive, commanded, compelling, constraining, decretive, demanded, enforced, exigent, forced, forcible, imperative, incumbent upon, indefeasible, indispensable, inescapable, irresistible, irrevocable, mandatory, necessary, obligatory, peremptory, prerequisite, prescriptive, pressing, required, requisite, restraining, restrictive, stringent, unable to be evaded, unavoidable, unpreventable, urgent, vital, without choice
associated concepts: compulsory arbitration, compulsory counterclaim, compulsory education, compulsory insurance, compulsory joinder of parties, compulsory performance of duties, compulsory testimony
binding, choate lien, compelling, essential (required), exigent, forcible, imperative, indispensable, involuntary, mandatory, necessary (required), obligatory, peremptory (imperative), positive (prescribed), prescriptive, requisite, stringent, unavoidable (inevitable), urgent
Burton's Legal Thesaurus. William C. Burton. 2006
The Essential Law Dictionary. — Sphinx Publishing, An imprint of Sourcebooks, Inc. Amy Hackney Blackwell. 2008.
adj. Compelled, mandated, obligatory, or required, especially if by legal process or a statute.
Webster's New World Law Dictionary. Susan Ellis Wild. 2000.