'avellan' originates from Latin, specifically the word 'avellana', where 'avellana' meant 'hazelnut' (itself named after the town Avella in Italy).

'avellan' entered English via Medieval/Old French forms such as 'aveline' and from Medieval Latin 'avellana' (named after Avella); the Latin term ultimately gave the botanical name Corylus avellana (the common hazel), and the English adjective/noun 'avellan' derives from these usages.

Initially, the term referred specifically to the hazelnut itself ('hazelnut'); over time it was also used adjectivally to describe a hazel or nut-brown color, broadening from the concrete nut to the color named after it.