OHZ or Ohz refer to: Optimistic habitable zone, see Habitable zone for complex life#Named habitable zones Original Heidelberger Zylinder, printing press from Heidelberger Druckmaschinen OHZ, common abbreviation for district Osterholz (and town Osterholz-Scharmbeck), Lower Saxony, Germany; in particular the first part of the regional license plate number, also in designations with a corresponding reference to district or town