essential
Despite the essentiality of water to all life, there is still much we don't understand about it.
The governments all agreed on the absolute essentiality of solidarity.
He wanted to know why they couldn't understand the essentiality of his work.
Any doctor will confirm the essentiality of regular exercise for physical and psychological health.

SMART Vocabulary: related words and phrases

Important and essential things
-based
amenity
at the core of something
bare
be-all
focal point
foreground
fulcrum
fundament
grandaddy
heavyweight
hot button
imperative
need
nexus
nitty-gritty
nub
nucleus
the grandaddy of somethingidiom
the name of the gameidiom