adj.不可缺少的,
Merriam-Webster Online Dictionary
indispensable (adjective)1.
not subject to being set aside or neglected - an indispensable obligation
2.
absolutely necessary - essential an indispensable member of the staff
Merriam-Webster Online Thesaurus
indispensable (adjective)impossible to do without
SYNONYMS:
all-important, critical, imperative, indispensable, integral, must-have, necessary, necessitous, needed, needful, required, requisite, vitalRELATED WORDS:
prerequisite; compulsory, mandatory, nonelective, obligatory; consequential, crucial, important, major, material, meaningful, momentous, significant, substantial, weighty; basic, central, fundamental, key, organic; insistent, persistent, pressing, urgentNEAR ANTONYMS:
undesired, unwanted; inconsequential, insignificant, unimportant; excess, external, extra, extraneous, superfluous, surplus