adj. 基本的;必要的;本质的;精华的;
n. 必需品;基本要素;必不可少的东西;
💡 essent=be存在,本质 + ial ...的 → 必要的,本质的
"The essential thing is that the two of you ought to agree."
根本的问题是你们俩应意见一致.
近义:must, necessity, proviso, requirement, requisite, condition
反义:nonissue, needless, pointless, profitless, purposeless, redundant