essentialness
"Essentialness" is a noun that captures the quality of being absolutely necessary or indispensable. It is a fairly rare and formal word — most speakers prefer the shorter "essence" or "essentiality" in everyday use — but it is a valid English word with one clear meaning.
When something is so important that things cannot work without it, you can talk about its 'essentialness'. Think of it as the degree to which something is essential — how truly indispensable it is. For example, water is not just useful; its essentialness to life is beyond question.
formal writing, academic or professional contexts · Formal; relatively rare in modern everyday speech
The essentialness of good communication in a team cannot be overstated.