英和和英

being indispensable

an indispensable duty

absolutely essential

imperative―peremptory

an imperative duty

an indispensable implement

an indispensable means

to a vital degree

absolutely necessary

the degree of indispensability

to adhere to unessentials

anything that is not essential

urgent necessity

the degree of necessity

to be necessary

anything indispensable

have need of

an omission of a necessary matter

the level of needlessness

the state of being absolutely required

necessity of matter (be unnecessary)

necessity

without need

without any necessity

a condition of being unnecessary

to lack necessities

a thing which must be done

to be pressed by necessity

the essential factor

grim necessity