Which word refers to something that is indescribable or beyond words?

The word that accurately refers to something that is indescribable or beyond words is "ineffable." This term specifically denotes experiences, feelings, or situations that cannot be adequately expressed in language, often highlighting their profound or overwhelming nature. When something is described as ineffable, it suggests that it transcends the limits of verbal description, leaving one at a loss for words due to its extraordinary quality.

In contrast, "unimaginable" relates to something that cannot be conceived or imagined, which may imply a sense of disbelief or difficulty in grasping the concept rather than the idea of it being beyond description. "Inevitable" indicates something unavoidable or certain to happen, lacking the nuance of being beyond verbal articulation. "Extraordinary" describes something remarkable or exceptional, but does not inherently convey the notion of being inexpressible or beyond words.

Thus, "ineffable" is the choice that specifically captures the essence of being indescribable.