Which word would describe an item or situation that is beyond ordinary importance?

The term that best describes an item or situation as being beyond ordinary importance is "indispensable." This word conveys the idea that something is absolutely necessary and cannot be done without. It implies a level of significance that surpasses mere importance or necessity, suggesting that without this item or situation, a certain goal or function would be unachievable.

In contrast, "essential" could refer to something fundamental, but it doesn't carry the same weight of absolute necessity implied by "indispensable." "Critical" suggests urgency but may not always indicate an item's overarching importance in all contexts. "Fundamental," while also signifying importance, often relates to the basic principles or foundations of something, which might not encapsulate the idea of urgency or paramount necessity as effectively as "indispensable."

Thus, "indispensable" is the most precise choice for describing something that holds significance beyond the ordinary.