pre-noun adjectival
unparalleled; unequaled; unique
Pre-noun adjectival (rentaishi) meaning 'having no equal'; used in formal or literary contexts to emphasize unmatched quality or status.
彼は並びなき才能の持ち主だ。
He is a person of unparalleled talent.
この美術館には並びなきコレクションが展示されている
This museum exhibits an unequaled collection.
無類 is also a pre-noun adjectival meaning 'unrivaled' or 'matchless', but it is more common in modern usage and slightly less formal than 並びなき.
Compound of 並び (narabi, 'lining up, comparison') + 無き (naki, classical attributive form of 無し, 'not exist'). Literally 'there is no lining up', i.e., nothing can be compared to it.