Hazel n. : A shrub or small tree of the genus Corylus, as the C. avellana, bearing a nut containing a kernel of a mild, farinaceous taste; the filbert. The American species are C. Americana, which produces the common hazelnut, and C. rostrata. See Filbert.

Hazel n. : A miner's name for freestone.

Hazel a. : Consisting of hazels, or of the wood of the hazel; pertaining to, or derived from, the hazel; as, a hazel wand.

Hazel a. : Of a light brown color, like the hazelnut.

Example:
What hair color would bring out my Hazel eyes?

Taxonomy
nuts, involucre, Corylus, genus, hazels, Filbert, different species, Common Hazel, spiny, free encyclopedia, Southeastern Europe, trees, Edible nuts, family Betulaceae, Turkish Hazel, husks, the leaves, Kew.

Defination from the web:
Hazel: note the spiny involucres (husks) surrounding the nuts. They have simple, rounded leaves with double ... There are 14–18 species of hazel. ... The Common Hazel is the species most extensively grown for its nuts, followed in importance by the Filbert. ...