extraordinary; singular; incredible
Emphasizes that something is so unusual or remarkable that it has no equal. Often used in a positive or admiring tone, but can also describe bizarre or outlandish things.
His talent is extraordinary.
This dish has an incredible flavor.
無類 means 'matchless' or 'peerless' and is often used in compounds like 無類の強さ (unmatched strength). 珍無類 combines this with 珍 (rare) to stress both rarity and uniqueness.
Compound of 珍 (rare, curious) and 無類 (matchless, peerless). The exact historical derivation is uncertain, but the word is conventionally associated with the meaning 'so rare it has no equal'.