adjective / noun

necessary

NESS-uh-sair-ee/ˈnesəseri/

Needed or essential.

The axle is necessary for the wheel to function.

A wheel without its axle is shown beside the matching axle needed to make it work; necessary component, clean mechanical diagram, no instructions.

Etymology

neLatinnot

+cessLatinwithdraw, go away, yield

+aryLatinforming adjectives

The underlying image is “no backing away”: something unavoidable or impossible to evade. From that comes the sense of an indispensable requirement—something that cannot be omitted if an activity is to happen or work.

In context

CrashCourse2:15

A necessary condition is what’s needed – like, what must be present – in order for a thing to be a thing.

Language & Meaning: Crash Course Philosophy #26

More examples

Bring only what is necessary for the short trip.
A permit is necessary before work can begin.
They packed the bare necessaries into one bag.

Forms

necessary · necessaries

necessity noun — Something that is required or indispensable.

Similar words

essential: Emphasizes being fundamental rather than simply required.
required: Often imposed by a rule rather than inherent necessity.