What term refers to something that is without parallel or unique?

The term that denotes something without parallel or unique is accurately described by the word "unprecedented." It conveys the idea of an occurrence or situation that has never happened before, emphasizing its distinctiveness and uniqueness. When something is referred to as unprecedented, it highlights the absence of prior examples, thereby establishing it as extraordinary or unmatched in its context.

In contrast, "conformity" pertains to adherence to established norms or standards, and does not imply uniqueness. "Novel" suggests something new or original, but it doesn't necessarily carry the weight of being unmatched or without comparison. Lastly, "mundane" describes something that is ordinary or commonplace, directly opposing the notion of being unique or unparalleled. Hence, "unprecedented" is the most fitting choice for expressing the idea of being one-of-a-kind.