A special form of database to store spatial information. Originally this term was introduced by ESRI for their ArcGIS 8 software product family.
In the ArcGis world geodatabase simply means a combination of RDBMS and ArcSDE database engine. ArcSDE functions as filter between the (relational) database and the GIS software containing the functionality to store, retrieve and manipulate spatial data over many different databases from many different database vendors (such as MsSQL, Oracle and IBM DB2).