1660s, from Middle English culpe (late 14c.), of unknown origin. Kelper "native or inhabitant of the Falkland Islands" is attested from 1960.
Any of various brown, often very large seaweeds that grow in colder ocean regions. Kelps are varieties of brown algae of the order Laminariales, with some species growing over 61 m (200 ft) long. Kelps are harvested as food (primarily in eastern Asia), as fertilizer, and for their sodium and potassium salts, used in industrial processes. Kelps are also a source of thickening agents and colloid stabilizers used in many commercial products. See more at brown alga.