JSTOR: E. A. Sophocles, A Glossary of Later and Byzantine Greek
It’s old but its now free and sometimes useful. A Glossary of Later and Byzantine Greek E. A. Sophocles Memoirs of the American Academy of Arts and Sciences, New Series, Vol. 7 1860, pp. 1-624 via JSTOR: Memoirs of the American Academy of Arts and Sciences, New Series, Vol. 7 1860, pp. 1-624.
