Webster's Revised Unabridged Dictionary · 1913

Kelp

Kelp (kelp) , noun

[Formerly kilpe; of unknown origin.]

1.
The calcined ashes of seaweed, -- formerly much used in the manufacture of glass, now used in the manufacture of iodine.
2.
(Botany) Any large blackish seaweed.

Laminaria is the common kelp of Great Britain; Macrocystis pyrifera and Nereocystis Lutkeana are the great kelps of the Pacific Ocean.

Collocations (2)
Kelp crab (Zoology) , a California spider crab (Epialtus productus), found among seaweeds, which it resembles in color.
Kelp salmon (Zoology) , a serranoid food fish (Serranus clathratus) of California. See Cabrilla.