The first element of Adosinda is probably derived from Gothic "audo", equivalent to OE "ead" wealth, property, a popular prototheme found in names such as
Edward,
Edwin,
Edmund,
Odoacer etc.. The second element is as
Rene says a derivation of Gothic sinths (High
German sind, English sith — the a at the end is properly an example of the oblique case). Sinths/sind/sith is in widespread use throught the Germanic languages with the same wide variety of meanings. The primary sense seems to refer to duration or extent of time or distance, from which in all the languages are derived senses relating to travel, distance, time and frequency (three sith= three times). It survives in English in the abbreviated compound "since" (sith-hence). In onomastic use the sense seems to be that of travel of journey, of which there are a whole class of deuterothemes, icluding fær (fare), fæt (journey, path), lida (traveller), wæȝ (way), waþ (wandering).