essential
英 [ɪ'senʃ(ə)l]
美[ɪ'sɛnʃl]
	    - adj. 基本的;必要的;本质的;精华的
 - n. 本质;要素;要点;必需品
 
英英释意
- 1. anything indispensable;
 - "food and shelter are necessities of life"
 - "the essentials of the good life"
 - "allow farmers to buy their requirements under favorable conditions"
 - "a place where the requisites of water fuel and fodder can be obtained"