noun
Used as a noun meaning something indispensable or fundamentally important, often in formal or technical contexts.
このプロジェクトにはエッセンシャルな要素が欠けている。
This project lacks an essential element.
必要 is the common native word for 'necessary' or 'need', while エッセンシャル is a loanword with a more formal or technical nuance, often used in compound terms.
Borrowed from English 'essential'.