OSI a German tribe mentioned only by Tacitus ( Germ. 28, 43), as dwelling beyond the Quadi, in a woody and mountainous country. But their national customs, as well as their language, were those of the Pannonians. They were, moreover, tributary to the Quadi and Sarmatae. The exact districts they inhabited cannot be determined, nor do we know whether they had migrated into Germany from Pannonia, or whether they were an ancient remnant of Pannonians in those districts.
[L.S]