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Webster 1913 Edition

Noun.

[F.

varech

; of Teutonic origin. See

seaweed, wreck.]

The calcined ashes of any coarse seaweed used for the manufacture of soda and iodine; also, the seaweed itself; fucus; wrack.

Noun.

The French name for kelp or incinerated sea weed; wrack.

varec ‎(uncountable)

The calcined ash of coarse seaweed, used for the manufacture of soda and iodine.
- 2015, James L. Marshall, Virginia R. Marshall, 9: History of Iodine, Tatsuo Kaiho (editor), Iodine Chemistry and Applications, page 203,
  Potash was scarce because of the Napoleonic Wars (1803–1815), and Bernard Courtois had resorted to varec imported from the Brittany and Normandy seacoasts [5].
The seaweed itself; fucus; wrack.

varec m ‎(plural varecs)