Essential means
those who are doing something now.
Money Heist Season 1, Episode 11
Excuse me, but the sun is ESSENTIAL
for all life on Earth.
The Big Bang Theory Season 3, Episode 11
NOLAN: The ESSENTIAL setup
for every one
Westworld Season 3, Episode 8
No one comes in without wearing a suit.
Whoever is not ESSENTIAL here
Money Heist Season 1, Episode 13
Those who are not ESSENTIAL here
may leave.
Money Heist Season 1, Episode 11