0. A database is an organized collection of data. It is the collection of schemas, tables, queries, reports, views and other objects
1. A comprehensive collection of related data organized for convenient access, generally in a computer.
2. A database is a collection of information that is organized so that it can be easily accessed, managed and updated
Wikipedia https://en.wikipedia.org/wiki/Database (0.); http://www.dictionary.com/browse/database (1.); http://searchsqlserver.techtarget.com/definition/database (2.)