noun
Laminaria longissima (species of kelp)
A specific species of kelp; used in culinary and biological contexts.
ナガコンブはだし汁を取るのに適している。
Laminaria longissima is suitable for making dashi stock.
Generic term for kelp; ナガコンブ is one specific species.
Compound of 長 (naga, 'long') and 昆布 (konbu, 'kelp'). The exact historical derivation is uncertain, but the name describes the long shape of this kelp species.