1
: extremely important and necessary
As a fighter pilot, he knows that good vision is essential.
Reservations are essential [=necessary, needed] if you plan to eat there on a Saturday.
—often + to or forThe river is essential to the region's economy.
Food is essential [=necessary] for life.
—often followed by to + verbIt is essential to use the proper technique.
It's essential to arrive on time.
—often + thatIt's essential that we arrive on time.
2
: very basic : fundamental
Free speech is an essential right of citizenship.
The essential problem with this plan is that it will cost too much.
There's no essential difference between the two products.
plural essentials
: something that is basic or necessary : something essential
—usually plural
the essentials for success
He tried to teach them the essentials of physics in just a week.
a computer stripped down to its essentials
We only had enough room to pack the bare essentials. [=the things that are absolutely necessary]
Cite this Entry
“Essential.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/essential. Accessed 29 Jun. 2026.
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