REQUIRED Synonyms: 95 Similar and Opposite Words - Merriam-Webster
https://www.merriam-webster.com/thesaurus/required
WEBSynonyms for REQUIRED: mandatory, necessary, compulsory, incumbent, needed, urgent, obligatory, imperative; Antonyms of REQUIRED: optional, voluntary, elective, discretionary, unnecessary, chosen, unwanted, unimportant
DA: 87 PA: 97 MOZ Rank: 74