What is meant by the acronym JDBC?

JDBC is the acronym for "Java Database Connectivity". JDBC actually offers a two-way interface towards a specific database (like for example Oracle or DB2) and to the actual Java application. The technical part towards the database is encapsulated in a vendor-dependent "database driver", but the part towards the Java application is totally vendor independent. Hence if the database gets replaced by a different vendor mostly no coding changes are necessary.