D defs.my
Entry 2 senses Webster, 1913

Compulsory

/kəm-pŭl'sə-rē/ · Com·pul·so·ry · IPA /kəmˈpʌlsəɹi/
01 a. Having the power of compulsion; constraining.
  1. 1.
    Having the power of compulsion; constraining.
  2. 2.
    Obligatory; enjoined by authority; necessary; due to compulsion.
    “This contribution threatening to fall infinitely short of their hopes, they soon made it compulsory.” Burke.