Where does “aar” come from?

aar (Dutch) comes from Middle Dutch âer, from Old Dutch ār, from Proto-Germanic ahaz, from Proto-Finnic ahtas, from Proto-Baltic anśtas, from Proto-Indo-European h₂énǵʰus, from Proto-Indo-European h₂enǵʰ- — to constrict, tighten, compress; narrow, tight;...

aar (Dutch): ear; eagle; Alternative form of ader