ETL:
Extraction, Transformation and Loading. Activities required to populate data warehouses and OLAP applications with clean, consistent, integrated and probably summarized data.
From: www.olapreport.com/glossary.htm

Extract/Transform/Load: This is the process of extracting data from their operational data sources or external data sources, transforming the data which includes cleansing, aggregation, summarization, integration, as well as basic transformation and loading the data into some form of the data warehouse (ODS, enterprise data warehouse, data mart). ETL can also refer to the vendor software that performs these processes.
From : it.csumb.edu/departments/data/glossary.html