iassium
Could not find Iassius in Logeion dictionaries. Looking for closest alphabetic form.
Jas, in Charta ann. 1473. ex Schedis D.
de Mazaugues, et in Conventione ann. 1522. ex Archivo Eccl. Massil.
Quoddam casale totum situm in loco de Alpibus, prope magnum Jassium, etc.Vide supra Jassile.