Arcadius Avellanus, born Mogyoróssy Arkád (6 February 1851 – 16 June 1935), was a Hungarian American scholar of Latin and a proponent of Living Latin. Mogyoróssy was born in Esztergom. Few details of his life in Europe are known with certainty; he is said to have spoken Latin as a child before he was fluent in Hungarian. He studied extensively in Europe and used Latin whenever possible, in preference to any other language. He emigrated to the United States in 1878, where he adopted a Latin translation of his original name; the common hazel is "mogyoró" in Hungarian and Corylus avellana in Latin.