fraxinetum

From frāxinus (“ash tree”) +‎ -ētum (“grove”). Attested from at least the early eighth century, per the quote below.

frāxinētum n (genitive frāxinētī); second declension (Early Medieval Latin)

1. ash grove
   • 724 CE, Diploma of Theuderic IV of France:

     […] indeque ad montem Cuoberg, per fraxinetum, ad locum qui vocatur Oschowa […]^[1]

     […] and from there to Mount Cuoberg, through the ash grove, to the place called Oschowa […]

Second-declension noun (neuter).

• Walther von Wartburg (1928–2002) “fraxĭnus”, in Französisches Etymologisches Wörterbuch, volume 3: D–F, page 772