What is Source ?
Source is (noun) 1. a place where something comes from I think the source of the infection is in one of your teeth. The source of the river is in the mountains. You must declare income from all sources to the tax office. at source (of tax on income) re- moved before the income is paid 2. a person or thing which is the cause of something The children are a constant source of worry. Polluted water is a possible source of cholera.
source: Easier English, Student Dictionary Upper Intermediate Level