German Geist means... ghost or spirit... while Geiz means stingy or miserly.
What do you mean by Hungarian plural? SZ is simply a character in the alphabet which has a sound like esz, versus es for S and ze of Z.
Can I assume that Mathias was the son of John (Janos) and Gertrude who settled in Cincinnati OH? If so John's WW II Draft Reg gives his birthplace as Billed, Hungaria... which was in the old Banat and if this is the family they arrived via Canada to the US
Biled, aka Billéd, Billét, Billiet, Bille located 269.6 miles WNW of Bucureşti 269.6 miles WNW of Bucureşti
The link below will take you to a Banat genealogy web page, which includes Billed