Microsoft) SQL Server Integration Services. A tool from Microsoft for easing the integration, cleansing and analysis of data from multiple, heterogeneous information sources.
Means that something (an object or system) consists of a diverse range of different items. It is the antonym of homogeneous, which means that an object or system consists of many identical items.
For a very thorough resource of more definitions, have a look at this site with a glossary of IT Terms with links : http://www.cryer.co.uk/glossary/