obligatory

adj

Etymology: From Middle English obligatorie, from Latin obligatōrius.

1. Imposing obligation, legally, morally, or otherwise; binding; mandatory.

   “an obligatory promise”

   “[…] if he speak the words of an oath in a strange language, thinking they signify something else, or if he spake in his sleep, or deliration, or distraction, it is no oath, and so not obligatory.”

2. Requiring a matter or obligation.