In the FDA document Guidance for Industry
Questions and Answers Regarding Food Allergens, including the Food Allergen Labeling and Consumer Protection Act of 2004 (Edition 4)* In section II Questions and Answers question 25 [Added October, 2006] Section 201(qq) of the Act defines the term "major food allergen" to include "tree nuts."
The following are considered "tree nuts" for purposes of section 201(qq). The name listed as "common or usual name" should be used to declare the specific type of nut as required by section 403(w)(2). Coconut Cocos nucifera L. (Arecaceae (alt. Palmae)) is listed.
On the Library of Congress website http://www.loc.gov/rr/scitech/mysteries/coconut.html Coconut is defeined as: Coconuts are classified as a fibrous one-seeded drupe.
Coconut is not a nut