noun
(countable) A tree or shrub of the genus Corylus, bearing edible nuts called hazelnuts or filberts.
(countable) The nut of the hazel tree.
(uncountable) The wood of a hazelnut tree.
(countable and uncountable) A greenish-brown colour, the colour of a ripe hazelnut.
(mining, countable) Freestone.
adjective
Of a greenish-brown colour. (often used to refer to eye colour)