Noah Webster's Dictionary 1. (a.) Mandatory; forced; required. 2. (a.) Obligatory; enjoined by authority; necessary; due to compulsion.

Multi-Version Concordance Compulsory (1 Occurrence) Esther 1:8 In accordance with the law, the drinking was not compulsory; for so the king had instructed all the officials of his house, that they should do according to every man's pleasure. (WEB)